Remove device and message endpoints sources from endpoint project.
Removed goal from AE pom as per Endpoints docs.

- See
https://developers.google.com/appengine/docs/java/endpoints/getstarted/backend/configure_pom.
Drop GCM classes.
Use 1.17.0-rc of google-api-client-android and google-http-client-gson.

- Replaced jackson with gson client.
Include show endpoint lib via jar file.

- Drop sources for show endpoint lib.
- Also drop currently unused gcm.jar.
Readme for AE project, add deployment strategy.