Fix for AllNodesExtraConfig and fix environment files to create swap files/partitions

Fix for AllNodesExtraConfig and fix environment files to create swap files/partitions

This submission:

 - Fix an error in the AllNodesExtraConfig resource.
   (Can't merge servers multiple times).
 - Add environment files to deploy swap file/partition
   without manual edit over the templates.
 - If a swap partition is mounted without having it available
   the deployment will fail, the fix checks that if the
   partition is not created then the deployment continues.
 - Removing empty extra lines in swap templates.
 - Adjust description and remove unnecessary comments in
   swap templates.

Closes-Bug: 1652184

Change-Id: I828bbbbd4c178956aac74af49f80fcd4f62fa16b