Access control scheme based on per-column ACLs and API keys

TODO: write more about it here
Use commit/rollback to force transactions to close

Makes postgres not die so badly all the time.
Add basic compiling of regex() to SQL

This only adds a backend for postgres for now.
Use the ARQ Substitute operator before compiling queries

This makes parameterised queries using the inputBinding able to
have the input bindings compiled into the query, instead of
being post-processed later.
Add trimAccess implementation for RegExp expression

Needed to merge regexp + ACL patches