Updated ContextTool to not add custom IConfigureHosting
Making Karl be an IPilkington.

Disabling flaky Redis tests.
Removed relational model and replaced with metadata model where needed.
Updated related code and tests.
Added tests to validate that issues #1077 and #1078 are fixed.
1077: Migrations: identity: false not respected when creating tables.
1078: Migrations: nullable: false not respected when creating tables.