Fix Safari support with only mp4

If only an mp4 stream is provided within the options (targeting iOS) the player would still attempt to add an empty WEBM src attribute. The fix will first check if there actually is an WEBM src before even checking if it's supported.
Fix resize issue

The top and left offsets weren't reset properly causing the video to offset strangely after resizing the window a few times.
use load() instead of play() method for looping.
Adaption to stretch poster image to fill video element
Fix readme support table
Muted parameter for a video
do not play video if autoplay is set to false

Signed-off-by: Jason Carney <jason@dashmedia.com.au>
Merge branch 'master' of github.com:andi/jquery.videoBG
Merge branch 'master' of github.com:Kaixhin/jquery.videoBG
Merge branch 'master' of github.com:JayCarney/jquery.videoBG
Merge branch 'master' of github.com:pROCKrammer/jquery.videoBG