Add integration with MongoDB and CongoMongo and enable saving new user
and listing existing ones

- Create mongo.clj file as a database support file which should contain
all functions for creating db connection and working with database
- Modify register.clj file to enable inserting a new user
- Add users.clj file to list all users from the database
Enable deleting an existing user and generating custom db ids when
inserting new users

- Add delete-user function to mongo.clj file and modify users.clj file
to enable deleting
- Add next-seq and insert-with-id functions in mongo.clj file for
generating custom db ids and inserting them to db
- Modify users.clj file to enable reloading a user list
- Move verify-register-form function from mongo.clj to register.clj file
Provide session management by noir.session from lib-noir library to
login page
Provide session management to register page
Allow access to users page only to the admin user

- Remove Users menu item for non-admin users.
- Add error message if non-admin user tries to access users page.
Add logout feature and change template to include main menu and user
menu

- User menu includes all user related features: Register, Login, Logout
and login information. If user is logged in, only login information and
Logout option are shown. If user is not logged in, Register and Login
options are shown.
Store session in database

- Use https://github.com/amalloy/mongo-session library for storing the
session in mongodb
- Add some minor changes
Change release version to 1.0.0