Extension cleanup

Fixes #145, making all the new extensions follow the pattern set by the new Template.

The native code is in the __NDK_project__ directory with the necessary project files so libraries and includes are set.

The extension is in the __ext__ directory with an ant build file to pull the built .so files into the right place and copy the whole extension to the SDK for use in an app.

A Sample is included in the __sample_application__ directory to show how the API works, and for testing.