Upstream biicode

This PR modifies (non-intrusively) the CMakeLists in order to use the www.biicode.com dependency manager.
It also adds a couple of files under the "bii" subfolder.
Included a .travis.yml proposal for initially handling travis-ci builds.

Please check:
- Biicode block: http://www.biicode.com/diego/glfw
- Biicode documentation: http://docs.biicode.com/c++/examples/glfw.html
- Github fork: https://github.com/drodri/glfw
- Travis build: https://travis-ci.org/drodri/glfw
This is not less intrusive. Duplicating existing code makes the change larger than it needs to be, doubles the future maintenance burden and significantly increases the risk of bugs.