various Improvements

Variables:
- added class option "playoutAnimations" -> when scrolling past the
animation should they be played out (true) or just be jumped to the
respective last frame (false)? Does not affect animations where
duration = 0
- added private var "scrollContainerOffset" -> needed for mobile
implementations as usually a scroll container is needed. Documentation
will follow.
- renamed private var "didScrollCheck" to "doUpdateOnNextTick" -> this
is merely cosmetic, as I found the previous name to suggest that
something HAS HAPPENED, when in fact something WILL HAPPEN on next tick.

Methods:
- added private function "cssNumericPosition" -> it gets position
values set in css instead of the jquery position() or offset() returns.
This is needed for Pinned elements that are moved (animated) during pin.
- added public function "setScrollContainerOffset" -> setter function
for above mentioned Variable for mobile applications. Documentation
will follow.
- changed addPin
	-> added ne option "pushFollowers" used to define wether the pinned
element should "push down" following elements or scroll past them
	-> made spacers for every pin, also changed classname of spacers to
"superscrollorama-pin-spacer" to avoid collision with existing elements
in the dom
- changed "checkScrollAnim"
	-> changed a lot of stuff regarding spacers and animation regarding
the new pushFollowers option for pins.
	-> Animations with duration 0 will now be played without regard to
scroll position, just based on the time option passed to the tween
object
	-> added suppert for indefinitely repeated animations (TweenMax option
repeat = -1). They will be repeated within the animation/pin duration
or, if duration is 0 they will play below the start point and stop
above.
	-> added onPin / onUnpin parameters. They receive a Boolean Variable,
defining wether the callback was fired at the end (true) or the
beginning (false) of the pin.
small update regarding mobile the scrollContainerOffset implementation

made some changes for the calculation of the animation startpoint when
using the scrollContainerOffset values.
Mobile Documentation

Added demo files for mobile implementation of superscrollorama
small fix

somewhere the option to pass a pin element as a string got lost -
fixed...
Updated Documentation

included missing methods + added missing parameters + global options