Message part of log4net call is now also sent to Sentry. Appender now supports multiple DSNs.

Now captures console arguments in sentry output (when these are available). Updated to use SharpRaven 1.5.1.

Add information to log4net tracing log if Sentry has issues submitting events. Updated to use current release of SharpRaven & log4net nuget packages.

Updates dependency versions to synchronise with current SharpRaven nuget package.