Minimal implementation of classes and methods necessary to support the JWT functionality in System.IdentityModel.Tokens.Jwt (https://github.com/MSOpenTech/azure-activedirectory-identitymodel-extensions-for-dotnet).  This change is released under the MIT license.
Fix VS changes to .csproj file.  This change is released under the MIT license.
Add file comment headers.  This change is released under the MIT license.
Add compiler pragmas for conditional .NET 4.5 compilation