ci: initial travis CI support for Linux distros and MacOSX builds

ci: initial travis CI support for Linux distros and MacOSX builds

This has been used by myself in a branch for a while now and it is time
to bring it into master as a base for all future CI related work.
I plan to use the same scripts and other bits for Jenkins as well as
other CI systems later on.

What we currently cover with this setup are linux builds for three
different distros and MacOSX builds for two different versions.

Travis will only be called when new commits get mirrored onto our GitHub
mirror (which only happens once an hour). Expect delays on these builds.

https://travis-ci.org/Enlightenment/efl