Single todo list

Hey Oliver,

I'm nowhere near getting these to pass, but I'd really appreciate it if you could look over my code and tell me if anything stands out to you.  I've been at it all day, so I'm pretty sure my vision and perception is blurred.

These current error messages.
```
  1) Project manager creater TODO Successfully
     Failure/Error: click_button "Add todo"
     ActionController::RoutingError:
       No route matches [POST] "/lists/1"
     # ./spec/features/project_manager_creates_todo_spec.rb:8:in `block (2 levels) in <top (required)>'

  2) Project manager creater TODO With description missing
     Failure/Error: visit new_list_todo_path(list)
     NameError:
       undefined local variable or method `list' for #<RSpec::ExampleGroups::ProjectManagerCreaterTODO:0x007fcb33757f78>
     # ./spec/features/project_manager_creates_todo_spec.rb:17:in `block (2 levels) in <top (required)>'

Finished in 0.09717 seconds (files took 1.33 seconds to load)
2 examples, 2 failures

```
that `list = FactoryGirl.create(:list)` on the other scenario isn't visible in this one