Install angular.
Implement Problem#to_h.
Allow certain problems actions (show, create, update) to respond to JSON.
Rewrite the problems form using AngularJS.
Can delete newly created tasks.
Make AngularJS play nice with Turbolinks.
Remove unneeded stuff.
Ensure that all problems object in AngularJS have default fields set.
Merge branch 'angularjs'

Conflicts:
	Gemfile
	app/assets/javascripts/application.js
	app/views/problems/_form.html.erb
Add the JSON checkbox to AngularJS form.