Merge pull request #2927 from metabase/invite_notification_emails

.dir-locals.el

src/metabase/api/session.clj

src/metabase/email.clj

src/metabase/email/messages.clj

src/metabase/email/user_joined_notification.mustache

src/metabase/models/user.clj

src/metabase/util.clj

test/metabase/api/session_test.clj