Users and importing them and speed

This adds the users and stuff and some caching/fetching/storing whatever. Here's some performance numbers

Login with no friends in DB:
`Completed 200 OK in 3025ms (Views: 34.6ms | ActiveRecord: 190.2ms)`

Login with some friends in DB:
`Completed 200 OK in 2506ms (Views: 22.7ms | ActiveRecord: 52.2ms)`

Login with all friends in DB:
`Completed 200 OK in 1223ms (Views: 23.8ms | ActiveRecord: 3.5ms)`

Login with all friends and only calling Steam to get Users games list:
`Completed 200 OK in 935ms (Views: 27.9ms | ActiveRecord: 1.7ms)`

Please review @carsonb @davefp @dan-menard