Replaces code contract reference with Requires class.
Fixes namespaces of certain platform-specific projects.
Fixes some NuGet package files for Mono platforms and adds them back to the package.
Removes TPL.Dataflow dependency from NuGet package for Mono platforms both because it's problematic and it's not actually a dependency.
Filled out AndroidCryptoProvider.
Turns out that AndroidCryptoProvider will compile entirely with .NET Desktop source code. Sweet.
Implements AppleCryptoProvider from a straight copy of source code from the AndroidCryptoProvider.
Adds missing MEF exports on Mono platforms.
Adds support for Google Cloud Messaging push notifications.
Wired up GoogleApiKey to web.config.
Fixes Google push notifications to actually work.
Adds Google Cloud Messaging push notification support to Relay service and IronPigeon helper client.