Add option to use http url instead of ssh url

[BrunoSpy]

Would it be possible to add an option to use git_http_url instead of git_ssh_url ?

https://github.com/phlegx/redmine_gitlab_hook/blob/master/app/controllers/gitlab_hook_controller.rb#L144

[phlegx]

@BrunoSpy try out release v0.2.2 and please read the new documentation under Installation -> 3. and -> 4. There are some changes (Gitlab Web hook parameter repository_git_url).