Changed MessageRecordListener to skip logging of polling jobs during testing.
Added missing call to RemoveListener when ExternalNode is disposed.
Hardening against race conditions in MessageContextualInfoProvider
Merge pull request #174 from DarthFubuMVC/mute-polling-job-log

Changed MessageRecordListener to skip logging of polling jobs during testing.
Merge pull request #175 from DarthFubuMVC/serenity-concurrency

Serenity concurrency
Locked NLog to 2.1