Make header link work correctly
Add 'ideas/idea/new' to router
Add IdeaNewRoute, which sets the `fields` property on its controller to {}
Add IdeaNew template, which reads from `fields`, calls `createIdea` action
Handle the `createIdea` action in IdeaNewController
Add 'New' link to main ideas page
Fix (multiple) issue where clicking New would barf

Okay, trying to take the training wheels off just a bit.

Running into issues with the way I did setupController.

First, I forgot to pass in the controller into the lambda.
Then, I ran into this. https://stackoverflow.com/questions/22254096/emberjs-cannot-delegate-set

Long story short, since we're not dealing with a bonafide model object, we use Controller instead of ObjectController.
Fix major design issue: New is nested under top-level Ideas, not an individual Idea

This fixes weird behaviour like:
* having a `new` url which contains the record you were just viewing (wtf)
* when clicking on `new`, not having the current record removed from display
Add (super, super) basic validation to the new idea page
Transition to idea after creating it
Remove `if isEditing` clause from edit template. Fixes bug, but not sure why.
Merge branch 'fix-edit-not-working' into ch19-creating-a-lead
Rails IdeasController: permit `idea_short`
Tweak CSS so floats don't collapse (at my preferred window size anyhow)
Fix issue where stale error is still shown when navigating back to 'new'
Merge branch 'ch19-creating-a-lead'