The bins' getcaps was bypassing the inner elements, and thus
failing to account for the caps transformations they allow,
which caused YUV video pipelines to fail with ximagesink, which
does not support YUV, even though the convenience bin includes
a colorspace converter for just this purpose.
https://bugzilla.gnome.org/show_bug.cgi?id=660816
These reconfigure based on the caps and plugin in converters if
necessary. This also makes switching between compressed and raw
streams work flawlessly without loosing the states of any element
somewhere or having running time problems.
