Support masked password in db connection properties file

This PR is addressing issue #81.

- [x] Reading encrypted passwords from properties file. (Based on AES key in Java KeyStore)
- [x] Key management utilities. Command line tools for password encryption
- [x] Add usage notes
- [x] Add shell script for "CRYPTO_APP" command line utility
- [x] Review & refactor code. (Things to check: maybe remove unneeded singleton caching in factories. Simplify some tests.)
- [x] Documentation (integrate it in official docs)