Depend on latest observer 2.0.0.
Depend on latest observer 2.0.0.

Reviewers: #material_motion, O6 Material Android platform reviewers, O2 Material Motion, featherless

Reviewed By: #material_motion, O6 Material Android platform reviewers, O2 Material Motion, featherless

Tags: #material_motion

Differential Revision: http://codereview.cc/D2181

material-motion/material-motion-android,material-motion/material-motion-android