Created admin interface to create category

* Dashboard admin view uses _category partial
* Added validations for location and category models
* Deleted duplicate sign-in/sign-out links in layout
* Modified category index view to delete create category form section
Corrected indentation for DashboardsController
Created Dashboard model to act as Presenter Pattern for locations & categories

* Updated CategoriesController to use Dashboard model
* Updated admin view to reflect use of Dashboard model
Changed CategoryControllers to remove Dashboard reference
Added flash message to layout/application
Merge pull request #4 from CraigstrJJM/md_admin_category

Created admin interface to create new category