Add hybridauth library.
Remove HybridAuth library.

This feature can be added later in order to let users to sign in with
external services (oauth).
Add the registration form.
Add link for register, login and logout actions in the menu.
Add logout file.
Add login page.
Correctly remove data when logout

Remove $_SESSION datas and cookie if exists.
Hide menu from unlogged users

When users is not logged the button to add markers is show in the menu.
Merge branch '2.0.0' of https://github.com/resilva/opendata into signin

Conflicts:
	application/assets/stylesheets/screen.css
	application/header.php
Check user right before adding markers

Check if the user has the rights before adding a marker to the map.