fixes #18481 - host index page loads faster

Fixes #18440 - removes dead code and obsolete permission

Fixes #18321 - added migration for builtin roles

fixes #13618 - cache expensive vmware api calls

fixes #17545 - adds UI notification support

- Initial data model for notification support, based on manageiq design.
- addes notification JSON endpoints.

fixes #18130 - add autoincrement for bigint id columns

fixes #18136 - add indices for reports type column

fixes #17899 - Delete instead of destroy orphaned records

fixes #13810 - increase value range for id columns

Fixes #17330 - skip admin email if it's unknown

When admin user is being seeded the Setting might not exist at that
moment. We can't just create it with value, since the setting would
be invalid because of other attributes. Therefore we split settings
creation from the setting list so we could create it from seed too....