v3.0.0

• Changes in sharing endpoints. See https://blogs.dropbox.com/developers/2016/02/more-breaking-changes-to-beta-sharing-endpoints/ for more details.
• Nuget package now contains separate assemblies for different frameworks. Projects target at .NET 4.5 or newer no longer need to depend on Bcl libraries.
• ID is now a required field in Metadata.
• Add PathDisplay to Metadata.
• Add ListMountableFolders endpoint in Sharing.
• Add DirectOnly flag to ListSharedLinks endpoint.