don't spawn a separate node process for running emulator
added dependency to npm package for chromedriver
make tests send well-formed (file://) url to checker
fix in detect invalid values for width / initial-scale
export list of expected values for viewport properties
more general handling of invalid values
use actually invalid value for initial-scale
adapted to new meta viewport handling
Merge pull request #45 from dontcallmedom/singleprocess-emulator

Singleprocess emulator