Renamed Delta plugin to Patch since it will be a bit more flexible

  By using the new naming standard, having both generation and application
  methods of deltas in one module not too bad. Methods were renamed to be a bit
  easier to flow in code as well.
Added tests to the system command

  Added verification that creating and applying the patch through the system
  call works with some canned files. Also added a -f flag to ensure that even
  if a file is overwritten that xdelta does not return an error exit code