add dashboard again

Update users_controller, change strong params
Update user model add accepts_nested_attributes_for location, delete null location
Fix error message
Add dashboard show erb
Add location partial
Change routes



Thanks Matt, I saw this in the doc: 
Sample usage (selecting the associated Author for an instance of Post, @post):

collection_select(:post, :author_id, Author.all, :id, :name_with_initial, prompt: true)