Refactor aquilon.client.optparser.Option.check
Refactor aquilon.client.optparser.Option.check

This documents and simplifies this method (from 11 lines down to 7, and
from four invocations of hasattr and getattr down to two).

Change-Id: I983148c48f5dfb9a990722955ad57c2517b6e4d7
Addresses-Issue: Jira/AQUILON-5546
Tested-by: Aquilon Template Build testing and verification
Reviewed-by: Raphael Beamonte <c1192f4cf4507fe239fa804ebe569f116d7ded40@morganstanley.com>

quattor/aquilon,quattor/aquilon,quattor/aquilon