Make it possible to register StubMapping
Added the preserve-host-header option when running in proxy mode
Removed configuration singleton (injected relevant values directly into ProxyResponseRenderer), renamed some config attributes.
Merge pull request #164 from kamilszymanski/register_mapping

Make it possible to register StubMapping
Now exits with a 1 when an exception is thrown from Jetty startup (e.g. port clash)
Allow wiremock servlets to be mapped at a different path than / in the current context.
Bumped version
Merging with upstream/master