Fix #72 : fallback solution for Safari iOS6 and Blob URLs

Safari for iOS 6 doesn't handle Blob URLs. There was already a workaround for Internet Explorer, so I used the same code for iOS 6.

I added https://github.com/ded/bowser to detect browser type and version. Then the browser is tested and IE / Safari iOS6 are now using the workaround.

See the issue #72