Possible bug in self.scrollOffset initialization.

Shouldn't `scrollOffset` be initialized with the current offset of the snap container? 

I'm using panelSnap for a project and with the current initialization (the scroll height of container[0]) I get huge initial `scrollOffset` values which cause the first scroll to always reset to the initially snapped panel.
Merge pull request #37 from aalexandrov/patch-1

Possible bug in self.scrollOffset initialization.