* fix(ios):use RCTConvert to convert url instead of using URLWithStringg
* fix(iOS):remove stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding, because it's deprecated in iOS 9
Apple required us to remove this (see #819)
BREAKING CHANGE: UIWebView has been removed
BREAKING CHANGE: useWebkit prop removal
BREAKING CHANGE: scalesPageToFit prop removal on iOS (since it's not compatible with WKWebview)
BREAKING CHANGE: Renamed RNCWKWebView to RNCWebView on iOS
hank121314
Thibault Malbranche
Jamon Holmgren