Made the JsonPacket(String, Exception) constructor invoke the JsonPacket(String) constructor.
Made the JsonPacket(String, Exception) constructor invoke the JsonPacket(String) constructor.

xpicio/raven-csharp,xpicio/raven-csharp,webaction/raven-csharp,getsentry/raven-csharp,getsentry/raven-csharp,getsentry/raven-csharp