Bind input to widget itself

[molfar]

https://github.com/danielm/uploader/blob/50fd2214c7236b4372651619c11111775adf1a47/src/js/jquery.dm-uploader.js#L274-L282

I think it would be good to bind input handler to widget element. Because in some cases input element can be dynamically replaced with new one, and its event handler would be lost. Moreover, it may be usefull to pass file field selector as config option.