username:{username}:uid should be a hash, not a bunch of keys

[julianlam]

Looks like we added these back when we first started playing with Redis and made everything keys.

Anyways -- this should be a single hash: username:uid, and all references to the old keys should change.

This is a breaking change that'll necessitate the running of node app --upgrade

[barisusakli]

Need to call node app --upgrade to fix the hashes. Also changed the email:username:uid keys to use hashes.