Commit 9db8eecac1 improved the
assert_raises_jsonrpc() function for better testing of RPC failure
modes. This commit completes the job by removing remaining broken
try-except RPC testing from the individual test cases and replacing it
with calls to assert_raises_jsonrpc().
This commit fixes the module-level docstrings for the tests and helper
modules in qa. Many of these tests were uncommented previously - this
commit ensures that every test case has at least a minimum level of
commenting.