This commit allows the user to configure two additional options that
were previously not configurable: Compression and DSAAuthentication.
Each config option is set as a boolean, and if left out of the config
will default to its previous behavior which is included and set to
"yes". If the user explicitly sets it to false, it will not be included
as an ssh option.
This adds two new SSH configuration options:
- `keys_only`
- `paranoid`
These values were previously hard-coded, but can now be user-specified.
Fixes GH-4275