Fold build output in travis-ci

Another cosmetic PR :smile:

* `cmake` and `make` steps are folded to reduce visible output.
* Colored one-line summary of build result is printed.

This seriously improves the build output readabilty, without loosing something... we can always
unfold the `cmake` and `make` output whenever it is needed.

See it in action: [here](https://travis-ci.org/EdVanDance/lime/builds/14655098)
Inspired by: http://enricostano.github.io/articles/dealing-with-travis-ci-console-output/