unplugged-system/cts/tests/tests/drm

- User of CTS code needs to edit configuration files in
  "src/android/drm/cts/configs/" according to the specification
  of user's DRM plug-in.
- If new plug-in is added, user should add corresponding configuration
  file under "src/android/drm/cts/configs/" and update
  "src/android/drm/cts/ConfigFactory.java".