Folder versioning params assume a specific order

[brwyatt]

The Augeas changes file assumes that the param nodes in the versioning node will always have the same order. This assumption has lead to incorrect setting of the params such that there are duplicate param nodes with the same key attribute, but different values.

         <versioning type="staggered">
             <param key="maxAge" val="31104000"></param>
             <param key="cleanInterval" val="3600"></param>
             <param key="maxAge" val="2592000"></param>
         </versioning>

In this case, the first "maxAge" param was added by the module, but the second one is the one which takes effect. Additionally, "cleanInterval" does not apply to staggered versioning (this was left over from manual configuration, so this being left over is not unique to this module, Syncthing is doing it, too).

The module should either edit the existing param node for the key, or remove all nodes that aren't managed (since there are only a handful of possible keys for each versioning type, it should be possible to do the full managed route if good defaults are used if not defined).