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
Moved padding from li to a in dashboard groups / projects listing
Removed redundant spans
Remove duplicated setupNoteForm method
don't lookup branch element - it might need to be escaped
Show percentage status on milestone detail page, fixes #485
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
Adding Spinach tests for 'search issues by description field' feature
Fixing requested changes for 'search issues by description' tests
Update redcarper gem
add missing config files to check during release process
Fix naming convention of LDAP tests
Disable allow_username_or_email_login in example

The example LDAP configuration in gitlab.yml enables the
allow_username_or_email_login setting. Because the effect of this
setting is somewhat counterintuitive, I propose we make 'false' the
example default. The settings initializer already sets this setting to
'false'.
Remove LDAP::Access#find_user

This method existed to allow LDAP users to take over existing GitLab
accounts if the part before the '@' of their LDAP email attribute
matched the username of an existing GitLab user. I propose to disable
this behavior in order to prevent unintended GitLab account takeovers.

After this change it is still possible to take over an existing GitLab
account with your LDAP credentials, as long as the GitLab account email
address matches the LDAP user email address.
Add CHANGELOG entry for LDAP takeover deprecation