Moved REST specific code to PayPalSDKCore from RestAPISDK
Updated stubs for open id connect and altered core packages
Updated stubs to use Newtonsoft
Updated stubs and REST classes for openid connect sdk
Updated REST base classes for openidconnect sdk
Moved REST specific code to PayPalSDKCore from RestAPISDK
Removed default constructor from RESTConfiguration, PayPalResource altered to call parameterized constructors of RESTConfiguration
Cleaned up code and updated code comments
Added Session, updated BaseConstants with open id url, Added User-Agent header to OAuthTokenCredential
added TestCase for OpenID
Merged core specific code from RestApiSDK
updated OpenIdTest.cs
Merge branch 'openidconnect' of https://github.com/paypal/sdk-core-dotnet into openidconnect