TIMOB-13494-make sure that image doesn't scroll beyond it boundaries

Behavior
If the image is in the original size, scrolling is not allowed
If the image is zoomed in, then it can be scrolled until the boundaries, images cannot be scrolled beyond the boundaries.

Fix for 
https://jira.appcelerator.org/browse/TIMOB-13494 and
https://jira.appcelerator.org/browse/TIMOB-13373