Move docstring inside relevant class
Move docstring inside relevant class

Per PEP 257 docstrings should be the first statement inside the class.

Change-Id: I5cbfc928b56ba8a967ce187a38d966de04f1954c

akash1808/python-barbicanclient,cloudkeep/python-barbicanclient,akash1808/python-barbicanclient,openstack/python-barbicanclient,cloudkeep/python-barbicanclient