This adds back in the unit tests that were removed due to charm-tools
issue #192  where the ignore option was 'ignored' by charm-tools.
This meant that the unit tests could not be ignored, and they ended
up in the built charm which then failed.
This adds unit tests to the interface-keystone and provides ostestr
support, and a makefile to allow easy 'make lint' and 'make test'
commands. All tests are performed in tox environments. At present this