Add extra option to the compression options

[Aaltuj]

Hi Damian,

Great work extending the github-release action.

I would like to make a suggestion regarding handling folders.

gzip: true
files: > 
VxFormGenerator.Components.Plain:VxFormGenerator.Components.Plain/bin/Release/ 
VxFormGenerator.Core:VxFormGenerator.Core/bin/Release/
VxFormGenerator.Components.Bootstrap:VxFormGenerator.Components.Bootstrap/bin/Release/

This will result in a .tgz file. containing: VxFormGenerator.Core.tgz\VxFormGenerator.Core.tar\VxFormGenerator.Core\bin\Release\*.*

Why not add an extra option flatZip that does the following: zip the content found in the folder: VxFormGenerator.Core\bin\Release\.

This would result in a VxFormGenerator.Core.zip containing only the data found at the Release folder.

How does this sound to you?