Disable padding by default.

ffmpeg_converter is adding a padding by default, but it shouldn't, because mostly you don't need that padding. Most web players are able to add that padding. So i want to turn off this feature. The settings for that have to go into the ffmpeg_wrapper settings form, I guess. See: #1269310: Add Option to enable padding.

But this module module also needs to be changed due it is responsible for the conversion, see: ffmpeg_converter_convert().

BTW: Hopefully the issue #1236572: Use ffmpeg_wrapper_convert_file instead of ffmpeg_converter_convert will be fixed, to not be required to change 2 modules.