Add concept model
Let users add concepts
Add a new concept with content
Display concepts with latest description
Allow user to revert description -WIP
Let users revert description edits
Fix error message for new concept form
Add multiple concept descriptions and ability to delete concept descriptions
Merge remote-tracking branch 'upstream/master' into concepts

Conflicts:
	Gemfile.lock
	config/routes.rb
	lib/user.rb
Add user to concept description
Fix specs
Fix revert button should show after first concept description edit
Fix Andrew's pull request comments
Update User.fetch_from_uuids method
Add links for concepts
Delete commented out text, fix styling
Merge pull request #38 from steelerose/concepts

Concepts
Fix spork/shoulda compatibility [#44]
Merge pull request #45 from AndrewLorente/shoulda-spork-compat

Fix spork/shoulda compatibility
Merge branch 'master' into refresh-tokens