Fix JSON client example and Update documentation. (#67)

* Updated the JSON client to be consistent with the library.
The JSON client requires two JSONs,
1. JOB json -- contains job description.
2. Config json -- contains configuration information such as username,
	password, schedulerUrl, zookeeper cluster configuration etc.

* Job json using docker-compose executor.

Used https://github.com/paypal/dce-go/blob/develop/examples/client.go#L50
to create a json file for a job that uses the docker-compose executor.
The current job json file (examples/job.json) uses an outdated version
of docker-compose executor. Once examples/client.go has been modified
to use examples/job_dce.json, it should be okay to get rid of
examples/job.json.

* Run thermos jobs using json client.

Added an extra field to JobJson, ExecutorDataFile, that holds
the path to the json file representing the executor configuration
data.
Added a new example job json file (examples/job_thermos.json) that
is to be passed to the json client along with the config file to
run a thermos job.

* Using scheduler URL instead of leader from zk.

The endpoints returned by ZKEndpoints(...) is not reachable
from outside the vagrant box. Hence, using the scheduler URL
directly.

* Added docs for using dce-go and json client.

* Place json client docs in separate subsection.

* Config now embeds realis.Cluster to be backwards compatible with
the python client cluster.json file.
Changed the type of Transport to string to stay flexible if new
transport types come up. JSON is used as the default transport option
is not transport is provided with the config.

docs/getting-started.md

@@ -94,6 +94,15 @@ client must be used in order to launch tasks using a custom executor. In this ca
 we will be using [gorealis](https://github.com/paypal/gorealis) to launch a task with
 the compose executor on Aurora.
 
+## Using [dce-go](https://github.com/paypal/dce-go)
+Instead of manually configuring Aurora to run the docker-compose executor, one can follow the instructions provided [here](https://github.com/paypal/dce-go/blob/develop/docs/environment.md) to quickly create a DCE environment that would include mesos, aurora, golang1.7, docker, docker-compose and DCE installed.
+
+Please note that when using dce-go, the endpoints are going to be as shown below,
+```
+Aurora endpoint --> http://192.168.33.8:8081
+Mesos endpoint --> http://192.168.33.8:5050
+```
+
 ## Configuring the system to run a custom client and docker-compose executor
 
 ### Installing Go
@@ -162,7 +171,7 @@ $ source $HOME/.profile
 
 Download and run the msi installer from https://golang.org/dl/
 
-## Installing Docker Compose
+## Installing Docker Compose (if manually configured Aurora)
 To show Aurora's new multi executor feature, we need to use at least one custom executor.
 In this case we will be using the [docker-compose-executor](https://github.com/mesos/docker-compose-executor).
 
@@ -263,7 +272,7 @@ A message from the executor should greet us.
 It is also possible to create a thermos job using gorealis. To do this, however, 
 a thermos payload is required. A thermos payload consists of a JSON blob that details
 the entire task as it exists inside the Aurora Scheduler. *Creating the blob is unfortunately
-out of the scope of was gorealis does*, so a thermos payload must be generated beforehand or 
+out of the scope of what gorealis does*, so a thermos payload must be generated beforehand or 
 retrieved from the structdump of an existing task for testing purposes.
 
 A sample thermos JSON payload may be found [here](../examples/thermos_payload.json) in the examples folder.
@@ -292,13 +301,32 @@ $ cd $GOPATH/src/github.com/paypal/gorealis
 $ go run examples/client.go -executor=thermos -url=http://192.168.33.7:8081 -cmd=create -executor=thermos
 ```
 
+## Creating jobs using gorealis JSON client
+We can also use the [JSON client](../examples/jsonClient.go) to create Aurora jobs using gorealis.
+
+If using _dce-go_, then use `http://192.168.33.8:8081` as the scheduler URL.
+
+```
+$ cd $GOPATH/src/github.com/paypal/gorealis/examples
+```
+
+To launch a job using the Thermos executor,
+```
+$ go run jsonClient.go -job=job_thermos.json -config=config.json
+```
+
+To launch a job using docker-compose executor,
+```
+$ go run jsonClient.go -job=job_dce.json -config=config.json
+```
+
 # Cleaning up
 
 To stop the jobs we've launched, we need to send a job kill request to Aurora.
 It should be noted that although we can't create jobs using a custom executor using the default Aurora client,
 we ~can~ use the default Aurora client to kill them. Additionally, we can use gorealis perform the clean up as well.
 
-## Using the Default Client
+## Using the Default Client (if manually configured Aurora)
 
 ```
 $ aurora job killall devcluster/www-data/prod/hello