User state agent (#112)

* Remove some variables from the RCRMQ class

The previous design was base on these assumptions:
  RCRMQ instance only need to do either publish or consume
  RCRMQ instance only need to interact with one single queue

However, in order to perform RPC-like call, an instance will need to do both
publish and consume. In addition, publish and consume are not necessary
to the same queue. So, save queue name as single variable inside the
instance is not viable anymore.

* Add exclusive queue support

* Check connection before bind queue

* Add auto-generate queue support

* Make bind queue optional when start consume

* Add properties support when publish msg

* Add user_state agent

* Add check_state in rc_util

* Add update_state in rc_util

* Add no-account when no hit in db

* Move valid state into config file

* Add user auth example

* Add migration flag

During the first phase, e.g. not all of users are in the user_state DB,
  using alternative method, getnet passwd, to see if user is an existing
  user.

* Update user state when using alternative lookup

* Allow no reply-to message to the user_state

* Add path for venv packages

* Fix typo

* Remove sys path to venv

* Fix condition for migration phase code

* Drop output from subprocess

* Move user_auth to top level

* Add default state as variable