pass most of pg db tests, working on adding UserInterest join
add user interest join table and create user method uses it
note an interesting rspec issue - this code causes rspec to stall - is it an infinite loop? I can't tell
Refactor uniqueness validation for UserInterest model
add update_user method and test to both dbs
update log in use case - now validated with github id instead of github login, also updates user's github login if it was changed on github