android pre-populated databases; support deleting databases on API < 16

Working on issue #10 -- Android part ready for review.  Tested on Android emulator for 4.4 (API 19) and 2.3 (API 10).  Also implemented deleting databases on Android API < 16 from discussion in #86.

This is my first experience with Android as well as my first pull request; critiques encouraged.
You actually shouldn't be modifying the JavaScript file; there's a CoffeeScript file that gets compiled to this, which you should use instead.  If you use the `./bin/test.sh` method to test, it will generate the file for you.

Also I doubt @brodybits will be enthusiastic about adding a new API method to be supported by all three platforms.  Why add `reset()` when we already have `close` `open` and `delete`?