Bug 892470: add more plugincheck redirects

Have bedrock handle these locales which are deleted on svn:
ak, en-GB, mai, my, nn-NO, nso, oc, sw, ta, ta-LK, ur, wo

These locales won't get updated any time soon and some are not shipped, it's better to fallback to the bedrock en-US plugincheck page than the old mozilla.com one
Merge pull request #1374 from pascalchevrel/Bug-892470_plugincheck_redirects_l10n

Bug 892470: add more plugincheck redirects