Install YDK without the pain

[wintermute000]

After wrestling with YDK (YANG development kit) installation for more time than I'd like to admit, I automated the thing in Ansible so I can reliably instantiate it at will.

0.7.1 has a convoluted install, hacks involved, and the documentation is.... eh.... (lets just say that parts contradict other parts, and parts that don't work aren't removed/caveated).

https://github.com/wintermute000/testvm-ansible/tree/master/roles/configure-yanghosts

YDK is this
https://github.com/CiscoDevNet/ydk-py