REST: cleaned up and added operations

- Deleted unused tests (there are integration tests in the (kie-tests) drools-wb-tests module)
- Added a GET /rest/organizationalunits call
- Removed BuildConfig POST content object from the maven compile, install and deploy calls, since
  it's no longer needed there

Still TODO:
- fix/finish DELETE /repositories/{repositoryName}/projects/{projectName}
? add DELETE /repositories/{repositoryName} call?
- finish/implement DELETE /organizationalunit/{orgUnitId}
- fix/finish POST /.../maven/test (doesn't look like it works!)
? implement stop/cancel job (see TODO in ProjectResource)