Set unifont-5.1.20080907.ttf for timeline on ZH projects

The original one, wqy-zenhei.ttc, doesn't actually exist in GDFONTPATH,
and EasyTimeline is not smart enough to make use of other system fonts.

http://paste.openstack.org/show/80352/ is a list of available fonts.

Bug: 20825
Change-Id: I9dd358872265ff753226b9c8f3b7cd374e3bf609