[poppler] Travis-ci.org buildbot

[Albert Astals Cid]

Hi, i just activated
  https://travis-ci.org/tsdgeos/poppler_mirror
based on my mirror at 
  https://github.com/tsdgeos/poppler_mirror

freedesktop git is of course still the official git.

The commits to run travis CI are only in github since they don't make sense in 
a global kind of way.

Also I had to enable a "custom" ppa to get a new enough glib since travis-
ci.org is only offering Trusty as a base, the rest seems to be good enough for 
now.

Cheers,
  Albert