NEW: More helpful message for 'sake dev/build' on new envs.

This change alters the no-db message on cli execution to give a bit more of a helpful set-up instruction.
The main motivation for this is so that composer can be set to run dev/build on post-install and post-update.

With that feature added, this will ensure that users installing with composer create-project won't be left
in the dark.

An improvement on this would be a shell script that interactively asked for details to populate this file
with, but one step at a time.
Merge pull request #2033 from sminnee/better-no-db-error

NEW: More helpful message for 'sake dev/build' on new envs.