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
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.
Show labels help message if last label is deleted
Fix tag tests

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Fix tests by using non-exist tag names

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Added search wiki feature
Merge pull request #7658 from Razer6/refresh_labels_page_on_delete

Show labels help message if last label is deleted
Merge pull request #7252 from unaheidi/master

Delete mailer queue
Merge pull request #7470 from bbodenmiller/patch-1

change git to git bin path