[Android] Add the core internal shell and the test project.

This patch is to add the core internal shell and test code for internal
shell.
All of the codes are modified from the core shell and core test project.
There are still many code here for multiple view support. You could probably reference https://github.com/crosswalk-project/crosswalk/commit/870836ab2752375d37097fb49ef372202b6f2cc1#diff-1530c8447e6ae2c76e52b8d7763c11ccL1 to remove the part to support multiple view.