replaced flash fallback with as3 variant

Built with Adobe Flash Builder 4.5 for Eclipse.
Used Flex SDK 4.5 .

added a new function in getUserMedia.js which allows to send various parameters to actionscript3 
(only options is to add width and height at the moment, with more functionality to come).

for this purpose you can add "fallbackmode" variable to the options. giving this variable the value "size" will send width and height to as3.
if you dont define a fallbackmode the webcamobject can be used just as before. 
(the main reason for this change is because as3 will always take the camera width and -height as stage-width and -height)

fallback tested and working on IE9 and IE10. (additionally to FF, safari and chrome)