Added MFA passcode and recovery code field for token requests.
Added endpoints for MFA-related activity: enabling MFA,
disabling MFA, generating a new MFA secret key, and
generating new MFA recovery codes.
Change-Id: Ia1443f05d3a2fecaa7f170f56d73c7a4e9b69ad5
This change removes all the separate implementations for
`apiservice.serveJSONError()` and defines one for every service to use
in `consoleapi/common.go`.
Change-Id: Iabf184e5cba69a98eb25936ce11ebd07f02c8ff3