jflte: clean up prop extraction process

* don't kill the blobs/ dir on /system so that it may be pulled
  from via extract_files
* this allows us to clean up the amazing mess i've created for
  the entire extract_files process

Change-Id: Ib93061faa693abf9762e56016c0b825a2494a3d4
Merge remote-tracking branch 'cm/cm-11.0' into kitkat