Added XML documentation to ErrorLevelConverter
Added XML documentation to ExceptionFrame
Added XML documentation to JsonPacket
Added XML documentation to LogScrubber
Added XML documentation to PacketBuilder
Added and changed the XML documentation for RavenClient
Added XML documentation to SentryException
Added XML documentation to SentryRequest
Added XML documentation to SentryStacktrace
Added XML documentation to SentryUser
Added XML documentation to SystemUtil
Merge pull request #42 from asbjornu/documentation

Adds XML documentation to all public classes, properties and methods, reducing the number of warnings from 49 to 3. The documentation should also be useful for anyone using the SharpRaven library.