fix edit option, scope todos so that users can have private todos, add landing page, all around styling with devise + logo

-renamed controller (to have "http://localhost:3000/todos" instead of "http://localhost:3000/todoodoos")
-renamed "association" to "user_role" (they are meant for the same thing, just different names)
-deleted some files (to save space) 

A lot of changes but anything can be replaced if so desired!
Hey Gabe! No worries! It's a small change. Feel free to ask questions whenever!