Hide option reference unless --full is passed

Summary:
A few people has voiced their opinion about the default help being to
noisy, and i agree myself. This limits the output to only show commands
+ synopses, unless you pass --full to help.

Test Plan: run a help workflow with and without --full

Reviewers: davidreuss

Reviewed By: davidreuss

CC: aran, Korvin, nh

Differential Revision: https://secure.phabricator.com/D3426