fix slow user lookup by name (#629)
fix slow user lookup by name (#629)

The user lookup was used non-indexed "user".name column which caused a
sequential scan, instead of the indexed lower("user".name)

Fixes #628
pajlada/pajbot,pajlada/pajbot,pajlada/pajbot,pajlada/tyggbot,pajlada/pajbot,pajlada/tyggbot,pajlada/tyggbot,pajlada/tyggbot