Merge pull request #809 from sdarlington/26d6cac1a75b3ffb24b3419904558a5ac1b6d264

Remove JSONKit
Minor code DRYup
Guard to avoid fetching shelf when not specified
Removed function to skip backup attribute

According to the iOS Data Storage Guidelines, files marked with a "do not backup" flag are not deleted in low-memory situations.
We should not mark as "do not backup" files that are in the cache and can be safely deleted.

Closes #595.
Merge branch 'master' of https://github.com/Simbul/baker

Manually fixed the following files:
	BakerShelf/BakerAPI.m
	BakerShelf/IssuesManager.m
	BakerView/lib/Utils.m