Add shortcuts for tag search and jira issues in forums

[goetz]

I just suggested some new shortcuts for the forums/wiki engine:

It would be nice to have a

• . [ [ Tag:licensing ] ]
  shortcut would link to the tag search at http://developer.qt.nokia.com/search/tag/licensing
  vote for it at "QTWEBSITE-397":https://bugreports.qt-project.org/browse/QTWEBSITE-397
• . [ [ QTCREATORBUG-5756 ] ]
  would link to the respective Jira issue at https://bugreports.qt-project.org/browse/QTCREATORBUG-5756
  vote for it at "QTWEBSITE-398":https://bugreports.qt-project.org/browse/QTWEBSITE-398

EDIT
the Jira shortcut is already here. Just write an issue id in the text and it will be linked automatically - so QTWEBSITE-398 is obsolete :)

[mgran]

We should still change the domain it points to, keeping it open until it's fixed :)