Stable branch for kf5 based projects created

[Albert Astals Cid]

It lives at 
  branches/stable/l10n-kf5/
in SVN

At the moment it only holds Plasma/5.0 translations that is the only project 
with a stable relase in the planning.

Plasma people please make sure you get the translations from there when making 
a release and that you give some warning before the release so people can do a 
last minute check on their translations.

Cheers,
  Albert