git-bundle support

[treylav]

Hello.

First of all, thanks for the useful tool.

Maybe I'm wrong, but I didn't find the repository packaging into git bundle among the ghorg features. In the meantime, this is a popular way to store repositories for backup: one file output, compression (although basic) without external software. It seems to me that it would be a logical addition to the functionality of ghorg.

Thanks in advance.

[gabrie30]

Thanks for sharing! Will probably implement when I have some time.