sockets now are stored in object with id instead of array
WebSocketBase now removes closed sockets from socket history
WebSocketBase should now support maxConnections (not tested yet)
wrote test for WebSocketBase #constructor and WebSocketBase #send, #ping, #close allow now sid to be a string or array
added test for providing sids as array in WebSocketBase #send
written test for WebSocketBase #assignSocket to work with maxConnections
Merge pull request #20 from bodokaiser/socket-storage

rewritten WebSocketBase socket management and added support for multiple sids