Added support for validating the password against a blacklist

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | 
| License       | MIT

Todo

- [x] Add tests (DependencyInjection)
- [x] Update README.md
- [x] Add better documentation
- [x] Provide a script (console command) for creating/updating a blacklist DB using the 500 worst passwords and such (http://www.skullsecurity.org/wiki/index.php/Passwords)
- [x] Add support for exporting a list (SQLite only)