Merge pull request #1768 from cdmoyer/Updated-new-db-migration-instructions

Docs: Update the instructions on creating a new database migration [ci skip]
Updated plugin to match newer ones, added tests.
Added insights plugin controller to plugin tests.
Added options to insgith controller.
Removed email option from insights plugin.
Added new notification_frequency field.
Added notification_frequency to owner.
Added controller frequency setting, dao and tests.
Added interface of setNOtificationFrequency and fixed docblock.
Added insight generator digest sending and first tests.