Fixes the case of the operations supported in the help message
of a resource.
Also fixes list of supported ops where we were listing all the ops
when a invalid op was specified instead of just the ops that are
supported *only* by the resource.
$ nsxadmin -r edges
Supported list of operations for the NSX-V resource ['LIST', 'CLEAN']
If user supplies -o LIST, it won't work. since the callback registration
is case sensitive. So to avoice any ambiguity we show the ops as lower
case.
Supported list of operations for the NSX-V resource ['list', clean'']
Change-Id: If41274181baf0f30502b8821169bbc6e4504ba2d
06cd0d5bf0