UI friendly fixes

* EditServerAction
 * If there is no server available to edit then display a helpful message

* SetDefaultServerAction
 * If there is no server available to set as the default then display a
   helpful message
 * Provide information dialog at the conclusion to tell the user that
   something has actually happened

* ModelExplorerResourceNavigator
 * Replace horrible grey border in default server status panel's parent
   composite with more consistent white.
WIP Doc