Revert "Fix compilation with GHC 7.8.3"

This reverts commit e9f58e15d2d38c154628d9f892469fdde40604c5.

This breaks compatibility of the on-disk format.
Add new Quotes database schema and migration

This one now has migration paths for the automatically, non-TH derived
SafeCopy instances which fail to compile with newer GHC.
Remove old Quotes database schema

Because it does not compile with newer GHC and our data is migrated now anyway.