Hooks refactoring

* replace update hook with pre-receive & post-receive hooks
* use pre-receive hook for authorisation
* use post-receive hook to create background job for GitLab worker

Related to https://dev.gitlab.org/gitlab/gitlabhq/issues/1516

See merge request !38

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Gitlab Access handles security check. GitlabPostReceive creates a sidekiq job
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Handle invalid number of arguments

See merge request !37

When a remote user with a valid SSH key runs something like 'ssh
git@gitlab.example.com foobar', gitlab-shell would raise an exception in
the GitlabShell#escape_path method. With this change, we catch an
invalid number of arguments as soon as possible and exit.

Update changelog

in light of !35

See merge request !36

Abort check path

Fixes #13

See merge request !35

Match .log* instead of .log.* in .gitignore

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Fix repository name/path extraction for GitlabUpdate

See merge request !34

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Update README Markdown style to match CONTRIBUTING

Something like gitlab-shell.log-20140626.gz will not be caught by the
original pattern match since '.' is taken as a literal character.

Adding support+tests for annotated tags.

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Use simplecov for development.

GitlabUpdate: use stripped path for repo_name

Improve coverage.

Use a default for gitlab_url that usually works

This default lets gitlab-shell connect to Unicorn directly, instead of
going through Nginx. This has the following benefits:

- the majority of users no longer has to edit the `gitlab_url`;
- avoid issues when the external GitLab web address does not resolve on
  the GitLab server itself;
- avoid SSL certificate issues.

See merge request !32