PolytomousKeyViewPart : added new method to get all the keys
plugin.xml: added menu and commands to refresh key list and key nodes
RefreshPolytomousKeyListHandler : handler to update list of keys
RefreshPolytomousKeyNodesHandler, RefreshNodesOperation : handler, operation to updated all keys nodes in the list
PolytomousKeyViewPart : added new method to get all the keys
plugin.xml: added menu and commands to refresh key list and key nodes
RefreshPolytomousKeyListHandler : handler to update list of keys
RefreshPolytomousKeyNodesHandler, RefreshNodesOperation : handler, operation to updated all keys nodes in the list