Stub for gitlab integration
Initial Gitlab Support
Fix Bitbucket merging conflict
Add gitlab options add admin page.
Add initial hook handler
Set gitlab_token column, and use ioutil for r.Body
Fix gitlab account re-link
Use TrimSpace
Stub for merge request hook handling.

GitLab merge request hook payload doesn't provide
any information regarding source commits.

And since Drone currently doesn't support manual fetch from another
remote upstream, merge request hook only supported for maerge request
fro within the same repository.
Refactor PullRequestHook signature.

May parse hook payload only once.
Set commit.PullRequest for PullRequestHook
Fix tests
A workaround to use fudanchii/raw-request branch without changing the import path.

At least until https://github.com/plouc/go-gitlab-client/pull/8
accepted or Drone officially fork it to `drone/go-gitlab` or
when we have package management which can do something like this:

gom 'github.com/plouc/go-gitlab-client',
  :github => 'fudanchii/go-gitlab-client', :branch => 'raw-request'
Merge pull request #237 from fudanchii/gitlab

Gitlab integration support