updated delete endpoint to return 204

- also bumped the version to 0.2.2
added delete logic

- also bumped the version to 0.2.2

Conflicts:
	src/main/scala/uk/gov/hmrc/cache/controller/CachingController.scala
merge from master
Merge branch 'master' into delete-from-mongo

Conflicts:
	project/HmrcBuild.scala
Merge pull request #3 from applethepeanut/delete-from-mongo

Delete from mongo logic