add user API (create and modify users)

- GET /users : get all users (optional arg include_user)
- POST /users

    {
        "username": "someuser",
        "passwors": "somepassword",
        "key": "somekey"
        "user_type": 1
    }

create a user
user_type is 0 for admin, 1 for normal user, 2 for apps ...
extra args will be saved
password will be encrypted before beeing stored in the db

- GET /users/<username> : get the username
- PUT /users/<usernname>

    {
         "passwors": "somepassword",
         "key": "somekey"
         "user_type": 1
     }
like post but update a user

- DELETE /users/<username> : delete the username
- PUT /users/<username>/password

    { "password": "newpassword" }

update the password

- PUT /users/<username>/key

    { "key": "newkey" }

update the user key.