Cadence 0.0.7

Issue by Issue

• Step over to stop out of async. #47.
• Add .js suffix to test file names. #54.
• Update t/sizes and t/test to work with a POSIX shell.
• Return cadence function directly instead of factory function. #49.
• Moved build directory contents to t. #51.
• Rename inner cadence function to async. #52.
• Consume events from event emitters. #48.
• An _ underbar as a step function name means to disable argument
  inference. #46. #25