'Query the device keys for a list of user ids hosted on a remote
server.
Request:
"device_keys": {
"<user_id>": ["<device_id>"]
Response:
"device_keys": {
"<user_id>": {
"<device_id>": {...}
Args:
destination(str): The server to query.
query_content(dict): The user ids to query.
Returns:
A dict containg the device keys.'

@defer.inlineCallbacks
@log_function
def query_client_keys(self, destination, query_content, timeout):

    path = (PREFIX + '/user/keys/query')
    content = (yield self.client.post_json(destination=destination, path=path, data=query_content, timeout=timeout))
    defer.returnValue(content)
