Remove from group action should log event

[ericnewcomer]

Perhaps related to broken migration?

[rowanseymour]

simulator coffeescript was missing handling of contact_groups_removed events - added in https://github.com/nyaruka/rapidpro/commit/733410ced1049c559925d8a2c8e09ad85a21cba0#diff-87cdfa5c7d9ec12184189698ad7ace08