0.5.0

• Browsers are now launched once for each run (previously, they were
  launched once per suite). This greatly reduces total tests run time,
  but can break some of your code, i.e. each mouseDown should always
  be closed by mouseUp.
  Previously, this was not required if mouseDown was used once for
  suite.
  It will show warning if versions of the modules does not match.
• flat reporter replaces tree. Tree reporter can not work with new
  browser launch model.
• Add parallelLimit option that allows to limit number of browsers
  run in parallel.
• Add suite.after() which can be used to perform some action after all
  of the states without taking screenshot.
• Unknown errors, returned by Selenium have more detailed report.
• Fix --version option.