Rescue `Parser::SyntaxError`s

If only I had written unparsable Ruby code, maybe I would have found
this before officially releasing the gem.
Suppress console output during tests

This is achieved by redirecting stdout and stderr to StringIO instances.
Test SourceControlDouble class

This test had been removed because it was noisy but it is back now that
I found a way to suppress console output during tests.
Bump to 1.0.1