RFE: support more eval options in deploy/server_config execute_query()

[mblakele]

When creating a deploy/app_specific.rb module to extend ml, it would be handy to have access to more eval options for execute_query. It looks like db_name is already supported, but a setup query might like to have access to the application code. So setting the eval module database and module root would be useful.

[dmcassel]

Paxton, I think substitutions get made in execute_query already, right? This may be a documentation problem.

[grtjn]

execute_query already supports both db_name as well as app_name. I think that should cover needs sufficiently.