Updates specs to use new rails5 format.
The old format:
`get :show, { some: params }, { some: headers }`
The new format:
`get :show, params: { some: params }, headers: { some: headers }`
Create a post-deployment migration to update all existing notification settings
with at least one custom level enabled to the new format. Also handle the same
conversion when updating settings, to catch any stragglers.
Add columns for each custom notification level, defaulting to null. Read from
those columns if non-null, otherwise fall back to the serialized column. Writing
will write to the new column if `events` isn't manually set.
