Attempt to launch headless browser.
1.5.4
Use html5 doctype

Without a valid doctype, IE will use “quirks mode” which is bad times.
For example, it will make IE9 behave like IE8 so methods like
`Array.prototype.indexOf` will suddenly be missing.
1.5.5
allow the user to specify the test harness via argv
Merge branch 'master' of github.com:spenceralger/testling

Conflicts:
	bin/cmd.js
Merge branch 'cli_harness'