* Move check from generated helper to test_help.rb, so that all
applications can benefit
* Rather than just raising when the test schema has pending migrations,
try to load in the schema and only raise if there are pending
migrations afterwards
* Opt out of the check by setting
config.active_record.maintain_test_schema = false
* Deprecate db:test:* tasks. The test helper is now fully responsible
for maintaining the test schema, so we don't need rake tasks for this.
This is also a speed improvement since we're no longer reloading the
test database on every call to "rake test".
There's no reason for guides to reference old behaviors. They should
be current as of the versions of Rails that they ship with, and including
older information just clutters thing.
I discussed this change with @fxn and he agrees.
