Update markdown reference to external issues

1. Issue may be not only in jira.
2. Rewrite method for support different external issue trackers
Delete mailer queue because we don't use sidekiq_mailer gem and now the mailer queue doesn't exist any more.
change bash to sh
fix bash-ism
Update markdown.rb

Fix mistake by @qqshfox report
fix link_to by @bwrsandman

Add missing '#'
add current sign-in date

add current sign-in date to admin section profile view
add missing config files to check during release process
Adding in snippet search functionality

http://feedback.gitlab.com/forums/176466-general/suggestions/5529795-search-though-snippets
Fine-tune the Remove Project redirect. Now it redirects to admin_projects_path and shows a flash message confirming the action has been taken.
change git to git bin path
added str-truncated to branch list to fix issue #7192
Changing some formatting for the Hound, modifying some UI text
Mention that people should use the CentOS tools.
Refactor Oauth::User class to use instance methods
Use instance methods of LDAP::User as well

Still in need of some proper cleanup
Move auth hash to a seperate class
Add new Gitlab::Oauth::AuthHash class
Show labels help message if last label is deleted
Fix tag tests

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