Feature: Limit checks by Scope

[gozer]

Right now, I can either run all checks or specifically select them. It would be nice to be able to select them by scope, something like:

$> aws-quota-checker check all
# Run only account scope checks
$> aws-quota-checker check --scope account all
# or run everything *except* account scope checks
$> aws-quota-checker check all,!scope:account