Allow per-node callbacks in verifyFormOutput

In the array of checks to perform, the second argument can now either
be a value to check for equality, or a callable that will be called
with the actual found value.  This lets you make more complex assertions.

Change-Id: Icb6f29af4160e9e47270fd7f4e66422d957bc28f
Canada backend tests

Also consolidated language providers in base test case

Change-Id: I0cee13000d459d31dde60047eeab3f7e90304481
Merge "Allow per-node callbacks in verifyFormOutput"
Merge "Canada backend tests"