Travis: add MAC OSX build

* Separate install dependencies instructions in two script files:
     * tools/travis.linux.install.deps.sh
     * tools/travis.osx.install.deps.sh
Travis: fix MAC OS X build

Apple: can't create bundle with a version specified for the dynamic library.
Merge pull request #87 from cchampet/build_MACOSX_Travis

Travis: add MAC OSX build