In Rails 5 assigning a value which is not explicitly `true` or `false` to a boolean column transforms it to `true`.
In Rails 4 it transforms the value to `false` with the deprecation warning:
```
DEPRECATION WARNING: You attempted to assign a value which is not explicitly `true` or `false` ("nil") to a boolean column. Currently this value casts to `false`. This will change to match Ruby's semantics, and will cast to `true` in Rails 5. If you would like to maintain the current behavior, you should explicitly handle the values you would like cast to `false`.
```
This commit fixes the spec that expects to receive Rails 4 behavior.
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.
If the Sidekiq job fails for some reason, a project can be 'stuck'
pending deletion. The project can't be viewed, so it shouldn't be
available through the notification settings association as this will
throw an exception when we try to show the link.
It will hold notification setting per group or per project. It will
allow get rid of notification level stored in Member model
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>