Add standalone bazel build

Test plan:

* Build artifacts
* Deploy javamelody-deps_deploy.jar to lib folder
* Deploy javamelody.jar to plugins folder
* Start Gerrit and verify Monitoring tab is shown and functional
* Verify no database statistics are shown in Monitoring page
* Add configuration to gerrit.config to activate datasource
   interception
* Restart Gerrit and verify database statistics are now shown in
  Monitoring page
* Generate project classpath and import it in Eclipse.

Change-Id: I6b7ce8a5abcb4a03798fc1a96f31df3df8ac060f
13 files changed