Dexie 2 support

[SparklingSoda]

Thank you for this nice and clean wrapper.
Do you have any plans on adding support for Dexie 2.0?
The compatibility seems to be quite good: http://dexie.org/docs/Deprecations

[aral]

@ddgll Just a quick nudge that this was implemented in d1a801d and it looks like the issue can now be closed :)