* Fix UNION syntax in resourcepermissions package. * Fix migrations in usermig package to work with Spanner. * Fix health query. * Use more connections for integration tests. * Add test-go-integration-spanner target to run integration tests against Spanner emulator. * Add test for enterprise. * Don't delete sequence number for migration_log.id column. * Only bump max open connections to 20 for Spanner. Lower integration test timeout.