hadoop: RedfishClient.java: simplify throw spec
hadoop: RedfishClient.java: simplify throw spec

FileNotFoundException is a subclass of IOException, so there is no need
to list them both in the throw specification.

Signed-off-by: Colin McCabe <3142ce8a0bdba4a38073365893e6b74f72d9c512@alumni.cmu.edu>

cmccabe/redfish,cmccabe/redfish,cmccabe/redfish,cmccabe/redfish,cmccabe/redfish