Add support for EpicsShutter.
Added checks whether self.instanceServer HO is correctly initialized before
trying to access it.
Added support for MD2v4_FastShutter to DuoStateBrick.
Bug fix: CommandReplyArrived: do enableCommand instead if no action (pass)
Replace exception with error message if lock file cannot be deleted after
closing the MxCuBE application
Merge pull request #2 from hellmig/esrf_visit

Esrf visit