Format the java code more nicely

Formats the code according to the age-old Sun Java
conventions, which most Java devs should find
easier to read.

This also removes the reliance on magic strings
in the execute() method.
Automate the unit tests and improve test coverage

This adds some structure to make it easier to
automate the unit tests.  With this PR, you can simply
run ./bin/test.sh ios or ./bin/test.sh android
and it'll automatically spin up an emulator and
run the QUnit tests.

I also went ahead and refactored the tests so that
you can now test both the native `openDatabase` and
this plugin.  That'll come in handy when you want to
test that the plugin behavior matches the native
behavior.