Support ff and chrome improvements

This modifieds the original project from https://github.com/dwa012/html5-qrcode master. It add the following:

* Fixes issues with Mozilla browsers both Android and Desktop
* Fix size of video on Mozilla Android (for now removing the configuration of the size of the video from the html5, it can be done directly on the js)
* Add support for multiple sources when using chrome on Android (Multiple cameras)
* Change the way is sent from the video to the canvas.
* Extract the timeout as a variable.