Target wpa81

Other changes:
* Add cross-target dependencies to net451 .csproj files
* Convert redis .csproj to net451
* Add missing TreatWarningsAsErrors elements
* Convert project.json code properties to arrays
* Remove redundant dependencies
* Remove test project versions
* Auto-format everything
Note, we're using a modified version of Ix-Async that we've uploaded to our MyGet feed.