Add syntax highlighting for fenced-code-blocks

This boils down to two changes:

+ Adding pygments to ``lib``
+ Changing the ``fenced-code-block`` options. Evernote doesn't allow class attributes on `div` or `span` so the styling needs to be done without classes. 

This will only work on python3 because the python3 version of pygments is the one included.

A sample note produced after this change is at:
https://www.evernote.com/shard/s49/sh/5afc2453-3d4c-4d38-a8be-d0deb1dcdfe8/0c6e2baac4a4c49830185093f1b0453d