Add anti-spam to invite/add emails

Add anti-spam to invite/add emails

Mandrill recently paused our email sending because someone was abusing our invites for spam, https://gitlab.com/gitlab-org/gitter/webapp/issues/2153

Plan

Afterwards


Number of people running into our disabled invites, https://sentry.gitlab.net/gitlab/gitter-backend/issues/799126


cc @rostrander

Edited by Eric Eastwood