This is a prelimininary fix for handling unexcepted/unamed arguments.
The ArgumentParser Class would catch the ArgException and return null.
But the calling method in ArgumentHandler Class would then try to access
the returning null object.
Only use package source that are enable
Merge pull request #504 from BlackFrog1/dev

Only use NuGet package source that are enable
Updated RoslynScriptEngine to create the host based on Type not on interface
Moved IScriptHost and IScriptHostFactory to contracts as they now don't cause any problems anymore
Fixed tests
Add ISCriptHostFactory to builder/overrides
Fixed build
Merge pull request #500 from BlackFrog1/CodeAnalysis

Fixes #499 - first part
Remove 'blank to exit' from REPL (#509)
Add exception handling in ReplCommand.ExecuteLine

To avoid infinite iterations in tests exceptions are used to stop Repl
execution.
Making '.csx' as default when no script name extension is provided.
Fixing bug on extensionless script running.
Fixing REPL bug.
Merge pull request #508 from filipw/roslyn-host

Change: Create ScriptCs host based on concrete type rather than IScriptHost interface
Merge pull request #512 from robsondealmeida/making-script-extension-not-required-for-script-execution

Making script extension not required for script execution.
Merge pull request #510 from marcob/dev

Remove 'blank to exit' from REPL (#509)