Code cleanup, added ability to attach logger, added CreateService api

* Code cleanup: Deleted multiple functions which have become stale. Removed cluster example as we replaced the need to create the Cluster object.

* Cleaned up ZK connection code by using the backoff function. Added a test to the end to end to test that we're getting the host correctly from ZK. Changed clusters test to be an outside package.

* Added LeaderFromZKURL test to end to end tests.

* Added logger to realisConfig so that users can attach their own Loggers to the client. Logger is an interface that shadows most popular logging libraries. Only Print, Println, and Printf are needed to be a realis.Logger type. Example in the client uses the std library log.

* Moved most fmt.Print* calls to be redirected to user provided logger. Logger by default is a no-op logger.

* Adding CreateService to realis interface. Uses the StartJobUpdate API to create services instead of the createJobs API.

* Bumping up version number inside client in anticipation of new release.

clusters_test.go

@@ -12,17 +12,18 @@
  * limitations under the License.
  */
 
-package realis
+package realis_test
 
 import (
 	"fmt"
 	"github.com/stretchr/testify/assert"
 	"testing"
+	"github.com/paypal/gorealis"
 )
 
 func TestLoadClusters(t *testing.T) {
 
-	clusters, err := LoadClusters("examples/clusters.json")
+	clusters, err := realis.LoadClusters("examples/clusters.json")
 	if err != nil {
 		fmt.Print(err)
 	}