Summary:
This change adds support for spring animations to be run off the JS thread on android. The implementation is based on the android spring implementation from Rebound (http://facebook.github.io/rebound/) but since only a small subset of the library is used the relevant parts are copied instead of making RN to import the whole library.
**Test Plan**
Run java tests: `buck test ReactAndroid/src/test/java/com/facebook/react/animated`
Add `useNativeDriver: true` to spring animation in animated example app, run it on android
Closes https://github.com/facebook/react-native/pull/8860
Differential Revision: D3676436
fbshipit-source-id: 3a4b1b006725a938562712989b93dd4090577c48