Added APParallaxViewDelegate protocol with optional methods APParallaxView:willChangeFrame: and APParallaxView:didChangeFrame:
Fixed delegate method names and updated demo project
Updated readme
Updated podspec
Initial implementation of min-height and added fix for scrollbar offset
Merge branch 'experimental/min-height' of https://github.com/apping/APParallaxHeader into experimental/min-height

Conflicts:
	APParallaxHeader/UIScrollView+APParallaxHeader.m
	Demo/APParallaxHeaderDemo/MasterViewController.m