Start acceptance test so admins can invite contributors to sign CCLAs
finish up basic implementation of creating an invitation to an organization
should autofocus email field
Starts to lock down invitations.

Adds controller spec to test that we attempt to authorize invitation
management. Adds goofy InvitationAuthorizer that ought to prompt us to
write a real implementation.

Also prohibits the current user from accessing stuff outside of their
organizations.
Minor grammatical change

Invite is a verb! :)
Remove pending spec
Send a rudimentary email when inviting collaborators
Users can click on the invitation link
Users must authenticate before accepting an invitation
add real authorization policy for invitations
fix invitations controller
update stubbing syntax to use allow instead.
use tokenable concern for invitations
implement mail_view
implement the ability for users to reject invitations
document and test Supermarket::LocationStorage
move some authorizer logic to the user
test invitations controller
add mail preview class
refine form_for syntax for invitations form