remove min-height burndown
Move tags directives to common module directory.
Simplify tgColorizeTags directive.
Minor improvements on tgTagLine directive.
Reset tags on issues/us/tasks on open create lightbox.
Remove unused local variables on main common module file.
Simplify the tg-check-permission directive.
Rewrite attachments directives and make them work as isolated components.

Also, it fixes #914 issue.