adding nuspec
adding nuspec

tonyeung/azure-activedirectory-identitymodel-extensions-for-dotnet,AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet,sandorfr/azure-activedirectory-identitymodel-extensions-for-dotnet,YOTOV-LIMITED/azure-activedirectory-identitymodel-extensions-for-dotnet,MSOpenTech/azure-activedirectory-jwt-token-handler-for-dotnet,larsw/azure-activedirectory-identitymodel-extensions-for-dotnet,AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet,AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet,AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet,wvdd007/azure-activedirectory-identitymodel-extensions-for-dotnet,tushargupta51/azure-activedirectory-identitymodel-extensions-for-dotnet