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 branch 'cm-11.0' of https://github.com/CyanogenMod/android_device_samsung_jflte into cd-4.4