Merge pull request #1 from markrendle/master

Optimized type checking in GibraltarEventProvider
Restored using statement for Gibraltar Agent Logging
Fixed NuGet package reference and readme
Merge pull request #2 from GibraltarSoftware/develop

Fixed NuGet Package Reference to restore Gibraltar.Agent.Logging features
Added a HashSet for excluded extension checking
Use Interlocked.Exchange when checking for null