Add Locker.get(id) method

get an item by id and decrypt meta and data
Change save definition current :      get an item param and save it or update existing ones.

previously :
    get a data and meta param and save a new item in db
Fix a callback call
Crypto.decrypt now return undefined if aes decryption or utf8 parse fail
Update jshintrc with jasmine globals
Fix tests comments
Replace angular-cache by a custom cache for encryptionKeys

 - put an object in cache reset expires timer
Fix default relock timer from 10 seconds to 5 minutes
Merge branch 'feature/fix-timed-relock' into develop