fixes the behavior such that we only toggle ungraded assignment counts
related to a particular user when his active enrollments in a given
course go from zero to one and vice versa.
also fixes performance issues in mysql. this required a custom trigger
body. see https://github.com/jenseng/hair_trigger/commit/326a10c for
the related hairtrigger commit to support this
Change-Id: Ie36b3d33ced69321f3a87468ab56480b1378d235
Reviewed-on: https://gerrit.instructure.com/6808
Reviewed-by: Jon Jensen <jon@instructure.com>
Tested-by: Hudson <hudson@instructure.com>
Cody Cutrer