Change convention to one sql file at top level, reorg a bit

Instead of requiring that a no-code quest:

1) Be <questname>.sql
2) Live in <questname>/sql

the convention is now just to have one single sql file in the top level
of the quest directory and it can have any name.

Along the way, factored out some stuff from sqlquest.coffee to more
appropriate modules.
Update basicexample to use new conventions
Loosen restrictions to allow more than just one sql file
Merge pull request #13 from scopely/simplesql

Change conventions for no-code quests