Rapl node capping daemon (#21)

* Initial work on rapl-daemon. Initial server set up. API to read max power per zone and API to write new power cap have both been written.

* Removing python script since this has been ported to go code now.

* Adding test for happy path retrieving max power.

* Change some data types around to avoid too much conversion.

* Add happy path test for cap zone

* Removing uncessary print statement.

* Change cap node to use a temporary setup.

* Renaming arguments to be more descriptive.

* Changing todo message.

* Changing test structure to only set up mock subsystem once and allowing functions to test on it later.

* Adding some more coverage for unhappy paths and fixing some values to reflect they are no longer floats.

* Keeping the old script around as it should be removed in a different PR.

* Delegating percentage check to capNode function.

* Fixing typo.

* Fixing typos.

* Changing shortWindow to longWindow as constraint_0 actually points to the long window.

* Renaming variable in test.

* capping funciton now returns which zones were sucessfully capped and which zones could not be capped. This information is now returned to the caller of the HTTP api.

rapl-daemon/README.md

@@ -0,0 +1,39 @@
+# RAPL Daemon
+
+This runs a server that is capable of changing the percentage at which
+a node is being throttled to using RAPL. This daemon should be installed
+on all worker nodes.
+
+### Sample payload for testing:
+```
+ curl --header "Content-Type: application/json" \
+  --request POST \
+  --data '{"percentage":75}' \
+  http://localhost:9090/powercap
+ ```
+
+### Payload
+
+```json
+{
+    "percentage":75
+}
+```
+
+### Response
+
+The daemon will respond with a json payload containing zones that were
+successfully capped as well as the zones that were not capped.
+
+```json
+{
+    "cappedZones": null,
+    "failedZones": [
+        "intel-rapl:0",
+        "intel-rapl:1"
+    ],
+    "error": "some zones were not able to be powercapped"
+}
+```
+
+Field error will not exist if failed zones is empty.