[Fix] Import <UIKit/UIWebView.h> for iOS.
Important for static libraries that do not import <UIKit/UIKit.h> in the Precompiled Header (pch).
[Fix] App crash when no handler (_messageHandler) for message from JS.
Merge pull request #97 from ruslanskorb/patch-1

[Fix] Import <UIKit/UIWebView.h> for iOS + App crash when no handler for message from JS.