[SetupWizardLib] Support for ObjectAnimator

Support for animator to animate SetupWizardLayout horizontally, which
requires adding a setXFraction method, changing the translationX with
respect to the width of the view.

Also moved annotations to com.android.setupwizardlib.annotations
package to avoid class loading problems in clients that use support
annotation library.

Bug: 20110840
Change-Id: Ibfb900323bcf4f32c8ded4c4a6dbf4765f17751a