[TIMOB-1555][TIMOB-13294] iOS: Shadows and clipping on Views

Addresses the following New Feature requests

[TIMOB-1555](https://jira.appcelerator.org/browse/TIMOB-1555)
[TIMOB-13294](https://jira.appcelerator.org/browse/TIMOB-13294)

Test using [KS PR 142](https://github.com/appcelerator-developer-relations/KitchenSink/pull/142)