'Get the versions on a endpoint from the keystone catalog
This method will make a GET request on the baseurl from the keystone
catalog to return a list of API versions. It is expected that a GET
on the endpoint in the catalog will return a list of supported API
versions.
:return: tuple with response headers and list of version numbers
:rtype: tuple'

def get_versions(self):

    (resp, body) = self.get('')
    body = self._parse_resp(body)
    versions = map((lambda x: x['id']), body)
    return (resp, versions)
