Update to version 1.2.1

From CHANGELOG:
   * Removed 1.2 Resolver and hardcoded whitelist of AARs to expand.
   * Improved error reporting when the "jar" executable can't be found.
   * Removed the need to set JAVA_HOME if "jar" is in the user's path.
   * Fixed spurious copying of partially matching AARs.
   * Changed resolver to only copy / expand when source AARs change.
   * Auto-resolution of dependencies is now performed when the Android
     build target is selected.
New Features
   * Expand AARs that contain manifests with variable expansion like
     ${applicationId}.
   * Added optional logging in the JarResolverLib module.
   * Integration with the Android SDK manager for dependencies that
     declare required Android SDK packages.

Change-Id: I006b47c17eb057a67b7bb5d8db23277ae3d7e6b7