add min_buffer parameter.

For live streaming reducing min_buffer allows us to switch from
a feed to another much faster.
resume stream when calling play and state was paused.
add function to prevent cache when loading fragments, and playlist.

with IE playlist can be cached which cause a live stream to end after
all inital fragments have been processed.
update chromeless test page with new api.
add a callback when video size is available, handle stage resize.