travis integration

[CasparKielwein]

FlexCore as an Open Source Project does currently not have integration of travis CI.
I tried to write a travis.yml file in my fork but travis uses an ancient version of ubuntu and compiler + cmake need to be installed in a more modern version.

I got it as far as to install clang and gcc in the proper version, but failed to get cmake 3.0+
( https://github.com/CasparKielwein/flexcore/blob/master/.travis.yml )