Fixes and oldVersion on onupgradeneeded

[andrehtissot]

1.Some fixes;
2.The event argument sent on onupgradeneeded now has oldVersion useful to partial database update - tested.

[brettz9]

@metagriffin : I'm not sure if you're still planning on developing the code at some point, but FYI, I've been putting a lot of work into adding Node support and ensuring better test compliance with the already rather robust IndexedDBShim on its master branch (not yet released). If you're not going to develop it, you might consider referencing the project as we have lots of tests as well (and working on adding the full W3C tests).