add docs and command support to set and unset metadata of objects
that are stored in an object store (swift).
Closes-Bug: #1501945
Change-Id: If838a4b3343b6ddb97cd4bd1cb63f0ba1c1a00a1
try and add some consistency with the show and delete commands.
replace 'show x' with 'display x'
change 'delete a y' with just 'delete y'
Change-Id: I47dfa8ee23ac5c41b355796415eb515155832f65