Add wsapi complete_transition

[ozten]

Add a new wsapi complete_transition - indicates that a user has been displayed the "transition to primary" screen.

AUTHENTICATED (assertion?) POST request

arguments: "email"

Side affect - will update the ? with ?

returns JSON object { success: boolean }

[ozten]

From lloyd's comments on a commit:

I think you should:

1. verify the the currently authenticate user owns the email address in question
2. verify the email address specified is a primary email address
3. update the database! set email.lastUsedAs to primary

Then I think in cert_email we need to update database and set email.lastUsedAs to secondary

[lloyd]

landed in 781184b