statsd/audit-logs: cleanup push/pull user agent code.

- add normalization
- add user-agent tag into statsd call so we can track protocol/vcs type usage
- internal merge also sends in repo type

rhodecode/model/pull_request.py

@@ -939,8 +939,9 @@ class PullRequestModel(BaseModel):
         return commit_ids
 
     def merge_repo(self, pull_request, user, extras):
+        repo_type = pull_request.source_repo.repo_type
         log.debug("Merging pull request %s", pull_request.pull_request_id)
-        extras['user_agent'] = 'internal-merge'
+        extras['user_agent'] = '{}/internal-merge'.format(repo_type)
         merge_state = self._merge_pull_request(pull_request, user, extras)
         if merge_state.executed:
             log.debug("Merge was successful, updating the pull request comments.")