userslug:{slug}:uid needs to be a hash, not a bunch of keys

[julianlam]

Same as #286

These keys should be replaced with a single hash: userslug:uid

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.