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:

- [x] Add WP8 project.
- [x] Figure out why some tests are failing. (Ed: It's because they suck)
- [x] Switch us back to AnyCPU, SQLitePCL-Raw will do the heavy lifting
- [x] Make Akavache.SQLite3 a true PCL and move encryption to Akavache core.
- [ ] Some other stuffs