Add @group WikibaseLib to lib tests.

This is the command I used:

sed -i '/@group Wikibase *$/ i\
* @group WikibaseLib' `ack-grep -l -v '@group +WikibaseLib'
-G ".*Test\.php" lib`

(The linebreak after i\ is significant, the linebreak before -G isn't)

Change-Id: Ic3d728290f9301c5556087224f0e7d3137f4451c
Merge "Add @group WikibaseLib to lib tests."