Implemented plugin creation and building in fpb

* `fpb --create plugin_name` creates a plugin structure
* `fpb --build plugin_path` builds repository, and
  packs plugin as tar.gz
* add run_tests.sh which runs pep8 checks and unit
  tests for fpb

Change-Id: Id4d108b7427869a5dc0200158d3e2c93c59a33ca
Implements: blueprint cinder-neutron-plugins-in-fuel