Use SQLitePCL-raw for Akavache-SQlite3

This PR update sqlite-net to be able to use SQLitePCl-raw from Eric Sink. It also pulls in SQLitePCl-raw. Note that it also includes the changes from #128.

To do that we can no longer have `AnyCPU` as a target. We need to target specific CPU architectures. I have added these for x86 and ARM, but we probably also need x64.
I am unsure how this works with NuGet.

## TODO:

- [ ] Add WP8 project.
- [ ] Figure out why some tests are failing.