- fix few bugs & add category edit form

	1. fixed bug: clicking on links to empty categories throws
		"Trying to get property of non-object " exception

	2.	fixed bug: when CMS is in a subdirectory of the www root,
			category links in dashboard point to the www root instead of the CMS base url.
			example: if the site's base url is : http://localhost/elena-cms/
			then a backend category link will be:  http://localhost/dashboard/category/3/article

	3.	added category edit form in backend
		to each category link, I added "Edit" button that leads to the form.

	4.	changed session cookie to "elenacms_session"
		to allow users to login to multiple laravel sites in a single window

	5.	untrack app.php

	6.	add artisan command for seeding new user
		php artisan db:seeduser --name="username" --password="password" --email="username@elenacms.somedomain"
	- fixed: article creation does not work
	- changed the fix for sidebar category links bug
	(fixed HTML::menuLink)