Password Hashing & Authentication Integration

Implement feature related to issue #40 (https://github.com/vitalidze/traccar-web/issues/40#issuecomment-64164343) and Password Hashing mechanism so that the plain password never travels plain text).
I guess you can approach same result in an easier way (just boolean arithmetic):

````java
boolean password_hashed = req.getParameter("password_hashed") != null && req.getParameter("password_hashed").equals("1");
````

Then I believe it's better to name variables in camel-case (like everywhere in code). So `password_hashed` becomes `passwordHashed`.