Travis CI: Don't install gstreamer0.10-ffmpeg or -plugins-bad
Travis CI: Don't install gstreamer0.10-ffmpeg or -plugins-bad

stb-tester and its unit tests don't require this; it's only necessary if
the user's "source pipeline" uses ffmpeg GStreamer elements.

We do need gstreamer0.10-plugins-base for videotestsrc etc (presumably
this was an implicit dependency of -plugins-base or -ffmpeg).

stb-tester/stb-tester,martynjarvis/stb-tester,LewisHaley/stb-tester,LewisHaley/stb-tester,wmanley/stb-tester,LewisHaley/stb-tester,LewisHaley/stb-tester,martynjarvis/stb-tester,martynjarvis/stb-tester,LewisHaley/stb-tester,wmanley/stb-tester,martynjarvis/stb-tester,wmanley/stb-tester,martynjarvis/stb-tester,stb-tester/stb-tester,martynjarvis/stb-tester,stb-tester/stb-tester,stb-tester/stb-tester,martynjarvis/stb-tester,wmanley/stb-tester,LewisHaley/stb-tester,wmanley/stb-tester,LewisHaley/stb-tester