Split up the WCSimWCDigitizer file into two files: WCSimWCPMT which handles the functions related to the PMT, and WCSimWCDigitizer which handles the functions related to the digitizer. This fixes issue #4
Adding in the new PMT files
Modified PMTDarkRate routine to work for new Digitizer scheme. Also, added logical volume info for the collection coming from the PMT.
Cleaning up
Removing unnecessary libraries
Changing the name of the new PMT collection for clarity
Merge pull request #17 from WCSim/feature/issue4

Merge branch Feature/issue4.  This will close issue #4.