Add arc close command

Summary:

arc close T1088 --status wontfix --message "I'm not going to fix this."

T1088 is the test task to screw with, so feel free.

Test Plan: `arc close T1088 --status [ resolved | wontfix | invalid | duplicate | spite | open ] -m "Message"`

Reviewers: epriestley

CC: aran

Differential Revision: https://secure.phabricator.com/D2162