Use TravisCI to verify compilation of example sketches

[prototypicalpro]

Is your feature request related to a problem? Please describe.
At the moment, the Loom team does not formally verify the functionality of the Loom examples or installation instructions, causing some examples to be "left behind" and no longer function after a feature updates (see #48).

Describe the solution you'd like
As an extra check, TravisCI should verify that all example sketches provided by Loom compile, to verify that the provided examples are correct and work with the setup instructions. The process TravisCI should use for building the examples should follow the Loom Installation Guide, including installing dependencies from the provided lists.