fix for chrome on iOS 6.1.3

In Chrome on iOS 6.1.3, calling Turbolinks.visit will fail because
browserSupportsPushState returns true, but currentState is still null
(because browserIsntBuggy returns false) and thus the cacheCurrentPage
function will fail. This one-line fix ensures that when
Turbolinks.visit is called, if either browserSupportsPushState or
browserIsntBuggy returns false, we fall back to simply setting
document.location.href.
remove .DS_Store file
Merge pull request #199 from fshowalter/master

Fix Turbolinks.visit in Chrome on iOS
Maintain CSRF authenticity token
Create changelog
Make it obvious where to listen for Turbolink events

It took me a minute to check the tests and confirm they're on `document`, may as well save people the time.
use :receive not :change
avoid creating unused results arrays

These functions are returning the results of their for comprehensions unnecessarily. Returning `undefined` ensures coffee doesn't store the results of the comprehensions, which is faster and less GC/memory intensive.
Merge pull request #202 from timruffles/patch-1

Make it obvious where to listen for Turbolink events
use return for nicer source/generated code
Merge pull request #203 from timruffles/patch-2

avoid creating unused results arrays
Update for Pull Request 203
Merge pull request #200 from reed/csrf

Maintain CSRF authenticity token - Fixes #171
Bump version to 1.1.1
Merge remote-tracking branch 'upstream/master'