🐛 Fix the SIP plugin along with the `get_info` method for `pyquid`

related to #5 (closed)

This merge request attempts to fix the buddies serialization for the sip plugin along with the quid.get_info() method for pyquid

>>> from pyquid import Switcher
>>> sw = Switcher('test')
>>> quid = sw.create('sip')
19:46:16.911         os_core_unix.c !pjlib 2.10 for POSIX initialized
>>> quid.invoke('register', ['user1@my_sip_server', 'my_secret_password'])
True
>>> quid.invoke('add_buddy', ['user2@my_sip_server'])
True
>>> quid.get_info('buddies')
[{'id': '0', 'uri': 'user2@my_sip_server', 'send_status': 'disconnected', 'recv_status': 'disconnected', 'whitelisted': True, 'status': 'online', 'status_text': 'On The Phone', 'subscription_state': 'ACTIVE'}]
>>> quid.get_info('buddies.0')
{'uri': 'user2@my_sip_server', 'send_status': 'disconnected', 'recv_status': 'disconnected', 'whitelisted': True, 'status': 'online', 'status_text': 'On The Phone', 'subscription_state': 'ACTIVE'}

Note that pjlib log level is too high and debug infos are printed to stdout.