Adding to melted api config

Signed-off-by: José Luis Di Biase <josx@interorganic.com.ar>
Use development common version

Signed-off-by: José Luis Di Biase <josx@interorganic.com.ar>
Added x264 to .travis.yml
removed avconv: using melt for video encoding

NOTES:
originally $(AVCONV) was "avconv" or "ffmpeg", but the argument -loop
was unknown to ffmpeg, and avconv was not in the project requirements
(to get avconv you have to install libav-tools).