logger: fix omission of prefix when injecting
injectedlogger: just forward options we don't touch in inject_logger
injectedlogger: allow 'as: id' parameter for InjectedLogger.use
README: a bit more documentation and examples
README: add gem version badge
injectedlogger: release 0.0.10
misc: some quick tests while we dont have specs
misc: add log4r to testing
misc: add a test for the new as option