0.5.6 updates

- Added sendStream() function for sending updated streams.
- Added SOCKET_FALLBACK attributes for fallback options.
- Added new event "channelRetry" for socket fallback re-tries.
- Updated "socketError" event with new param fallback. Related to SOCKET_FALLBACK.
- Added callback for getUserMedia() function.
- Re-structuring of Media stream parsing settings.
- Added tests for "stream" for stream parsing and getUserMedia and "sdp" for sdp modifications.
- Renamed methods _addStereo, _removeFirefoxH264Pref to _addSDPStereo and _removeSDPFirefoxH264Pref.
- Fixed bugs in _findSDPLine
- Added new method _setSDPVideoResolution to test modification of video resolutions.
- Moved userData from _user attribute to _userData attribute. _user attribute now stores signaling user information only.
- Moved stream settings to _streamSettings and _getUserMediaSettings
- Removed _handleLocalStream
- Added "mute" option parameter for sending muted streams
- Added muteStream() function for muting streams.
- Added fallback to long-polling for socket connection.
- Updated "socket" test for long-polling test and browsers with no WebSocket support.
- Added new global variable SkylinkLogs for users to store logs.
   - Added getLogs property function to get all the logs. Takes in the log level to return the certain level of logs only. Related to LOG_LEVEL.
   - Added clearAllLogs property function to clear all stored logs.
   - Added printAllLogs property function to print all stored logs in the console.
- Updated setDebugMode with options for users to set.
    - Enable "trace" for user to trace every log. Not supported in older IE browsers.
    - Enable "storeLogs" for users to store logs in SkylinkLogs.
- Call getPeerInfo() to get user information now instead of _user.info.
- Added async callback for sendStream().
- Fixed datachannel readyState issues.
- On leaveRoom() now stops mediastream.
- On joinRoom() or getUserMedia() will always re-get streams.