Allows user to unsubscribe from RFP blast emails either through settings page or unsubscribe page
Adds EmailPreference factory
JShint fixes
Require auth for email unsubscribe
Revert "Require auth for email unsubscribe"

This reverts commit 8a1eb4df45f48f3735c7d0ffa3be80390b143eac.
Merge pull request #739 from bountysource/sean/rfp_emails

Allows user to unsubscribe from RFP blast emails either through settings...