Shield examples

In this release, you can find ready-to-run examples for each of the Pycom sensor shields. As a result of refactoring the repository and in avoiding duplicate files, we will release updates to the shield examples in this way.

In this release:

• Combined the separate sensor libraries back to a single location
• De-duplicated pycoproc files into a single location
• Release zipfiles for each shield with examples, ready to run
• Included a makefile to generate the example projects from the new shields folder
• Added firmware-out-of-date error message in pycoproc2