GSF.COMTRADE: Fixed the AnalogChannel.PhaseDesignation property so that it does not return a null character as a string.
GSF.COMTRADE: Fixed the AnalogChannel.PhaseDesignation property so that it does not return a null character as a string.

git-tfs-id: [https://tfs.codeplex.com/tfs/TFS07]$/gsf/Main;C92224

rmc00/gsf,rmc00/gsf,GridProtectionAlliance/gsf,rmc00/gsf,rmc00/gsf,GridProtectionAlliance/gsf,GridProtectionAlliance/gsf,GridProtectionAlliance/gsf,GridProtectionAlliance/gsf,rmc00/gsf,rmc00/gsf,rmc00/gsf,GridProtectionAlliance/gsf,GridProtectionAlliance/gsf,GridProtectionAlliance/gsf