Improve nested console logic.

Remove command from program command list and issue warning on attempt to
nest consoles.
0.1.237
Central module for getting interactive prompts.
Migrate auth ask() to use prompt module.
0.1.238
Move interactive credentials helper to prompt.
Tidy whitespace.
Update interactive welcome.
Fix bug with database option handling.
0.1.239
Add interactive confirmation to admin/rm.
0.1.240
Call prompt.rm() in correct scope.
Warn on unacceptable prompt.rm() value.
Inject name in prompt.rm().
0.1.241
Support --no-interactive.

Handle mutually exclusive interactive command and option.
0.1.242
Fix admin tests.
Update db test fixtures.