Catch uncaught socket.timeout (OSError subclass).

Catch uncaught socket.timeout (OSError subclass).

Wrap first call of MPD._reset_cache in try/catch, but I don't understand
why...

During first connection, player cache is populated with MPD._reset_cache
Even though the connection to MPD succeed, we can receive a socket.timeout if
the proxy is not reachable (MPD server in satellite mode request another
MPD server for music library requests, for instance during _reset_cache).

The issue here is the OSError (socket.timeout) is not raised as it
should be, ie. wrapped in PlayerError within MPD.__getattr__.
MPD._reset_cache is calling list('artist'), which is actually going
through MPD.__getattr__, but when OSError is raised is is not
wrapped in PlayerError.

Launching mpd-sima against an MPD server on the same host but with a
database proxy over the network can trigger this socket.timeout:
  * Start MPD
  * Shutdown internet link
  * Start mpd-sima