Fix order of arguments in assertEquals

Part 1

Related to: bug #1277104

Change-Id: I9822a534d5082394dc5f64d911cd0a8fb1845018
enable a single worker by default

there are issues with postgresql and multiple connections. change
default to a single worker to still allow multiple workers for
backends which support it.

Partial-Bug: #1298073
Change-Id: I1bf256f333ad8614bcae2c74dc0544553bffbbe7
Merge "Fix order of arguments in assertEquals"
Merge "enable a single worker by default"