Fix package upload script

Merge pull request #13 from snakefoot/master

 GelfLayout - Supports ExtraFields and IncludeMdlc

Fix issue with custom field serialization error handling, if a field …

…cannot be serialised it will get ignored and won't throw exception to Nlog.

Change title to fix issue with uploading new version of the package.

Merge branch 'master' of https://github.com/farzadpanahi/NLog.GelfLay…

…out.git