Add unit test for libcloud API

src/main/python/stratuslab_usecases/api/testBasicVmLifecycleTtylinux.py: Ttylinux unit test
src/main/python/stratuslab_usecases/api/BasicVmLifecycleTestBase.py: Base class
src/main/python/stratuslab_usecases/api/libcloud-drivers-use-cases.ini: Config file to run with nosetests