Implement GaussianBlur effect rendering

[ystrot]

See GaussianBlur and Node.effect. Useful links:

https://dzone.com/articles/applying-gaussian-blur-to-uiviews-with-swift-proto
https://www.raywenderlich.com/84043/ios-8-visual-effects-tutorial

[ystrot]

This feature available in the master branch and will be part of 0.9.2 release.