Make sure links aren't caught by Phabot Rabbit

Test Plan:
set /bin/secrets to only be in jamestest room
bin/culturecow
type
D1234
check out D1234
http://phabricator.khanacademy.org/D1234
aD1

Make sure the frist two are responded to, but the last two aren't

Reviewers: csilvers

Reviewed By: csilvers

Differential Revision: http://phabricator.khanacademy.org/D14305