Enable developers to provide their own way of storing and getting the encryption key

[valentinstoychev]

Currently, the encryption key is stored inside the app. It will be good to enable developers to store the key in a different place they need (on a web server for example) and to provide it on demand.

[priyangamani]

Note: D:\FlashCashAPP\FCNativeScript\platforms\android\src\main\java\com\tns\Run
timeHelper.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
1 error
Incremental compilation of 3 classes completed in 0.564 secs.
:compileF0F1F2F3F4F5F6F7F8F9F10F11F12F13F14F15F16ReleaseJavaWithJavac FAILED

FAILURE: Build failed with an exception.