Updated build to work with NuGet disabled

Updated signatures for new NLog methods

Updated dependencies

Updated package references for NLog, Serilog, added nuspec for Serilog

Added ExitCode for unhandled exception so that service restarts

Added service events, adding unit test host, refactored service confi…

…gurators

Added service configuration documentation

Updated NuGet, hope it works

Updated version to 2.3

Can't internalize Spark