Add dont_compress to server module

[Natrinicle]

Allows rsync to skip compression on file types that don't compress
well such as already compressed files and binary files.

[TheMeier]

Could you please prameter documentation and a test to the PR?

[Natrinicle]

This is my first time writing Puppet tests and I'm hoping that I did that correctly based on what I could find. Just a heads up that additional scrutiny might be necessary.

[TheMeier]

LGTM

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