Add client redirect after accepting invitation.

[#81784306] https://www.pivotaltracker.com/story/show/81784306

Signed-off-by: Rob Gallagher <rgallagher@pivotallabs.com>
Enable sending invitation email via notifications service

[#77649332] https://www.pivotaltracker.com/story/show/77649332

Signed-off-by: Rob Gallagher <rgallagher@pivotallabs.com>
Merge branch 'feature/invitations' into develop