Return "Email" in User Identities

[mattdjenkinson]

If a user hasn't signed in with Google or GitHub nothing is returned in user identities (account settings). In staging we can log in with an email and password (being used for automated testing atm), it would be nice if this info could be returned in the user identities call so we can verify in the automated cloud portal tests that user identities works.

[eleven-arch]

Opened PR for this: #74

It adds a local email fallback to useridentities when a user has no linked Google/GitHub identity, so email-sign-in users now get a result instead of an empty list. External IDP behavior is unchanged.

[scotwells]

Confirmed @eleven-arch's changes in #74 are showing a new email based identity now in the staging environment. 🎉