GhostDriver should NEVER allow to disable JavaScript.

It would simple not work.
Thanks to issue #253 for making me notice this issue.
Implement `/maximize` command.

Issues like #269 highlight that some people just
assume "it should work".
So I have picked the most common resolution (currently)
and set it to it.
http://gs.statcounter.com/#resolution-ww-monthly-201307-201312

Will update if those stats change at some point.