feedback

switching to PassphraseKeyServices was easy with the existing merged impl, needed to refactor to store the salt for user convenience (that is remove the 'setSalt' step)  and started [at it here](https://gist.github.com/cvasilak/016e4b5f5ac2349da309). 
BUT have decided NOT, will leave it as it is and let the user provide the salt. Once the EncryptionService API discussion moves forward we can revisit.

so what I have done is:
- one-line fix in the encrypted memory storage.
- refactor encrypted store tests to use PassphraseKeyServices.
- added moar tests.