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

Execute command directly without using shell

More detailed warning about symlinks in repos_path

   use Shellwords.shellwords for splitting origin_cmd instead of .split(' ')

When that branch contain a '/' in the branch name.
Fix for git over ssh

Fix typos

The syntax for `sed -i` is incompatible between GNU sed and
BSD sed. By Tempfile from the Ruby standard library we can
avoid using the `-i` option of sed.

Support adding and removing branches and tags

Update config.yml.example for grammar

The previous commit has the code addition to support adding and removing branches and
tags in a repository - This commit ensures basic test cases are supported.

This commit adds support to create and remove branches and tags from gitlab-shell.

The code style was followed as closely as possible to the original.

The purpose of this commit is that I will be adding support to the Gitlabhq (Gitlab) project
in order to allow adding and removing of branches and tags through their API.