Thread-safety: Don't share request object between reqeusts
Added Kindle Fire HD support.
Add support for Windows Surface tablet
Update README.md

Man, I love this gem. Still so useful. Thanks for keeping it maintained.

I thought adding browser.version would be helpful in the README as a quick reference.
Updated gemfile.
Merge pull request #50 from chrisyour/patch-1

Update README.md
Merge pull request #49 from ajjahn/master

Add support for Windows Surface tablet
Merge remote-tracking branch 'ronald05arias/master'

Conflicts:
	lib/browser/methods/devices.rb
Merge remote-tracking branch 'derekclee/kindle-fire-support'

Conflicts:
	test/browser_test.rb
Merge remote-tracking branch 'nixme/threadsafe-middleware'
Bump up version.