RAM usage display in Science Portal UI

[kcasteels]

Currently the Science Portal UI displays Core and instances used. Often the cluster is RAM limited, not CPU limited, so users will see lots of cores available but be unable to launch sessions due to lack of RAM. Displaying RAM would help to inform the user better about resource availability. Optionally, displaying the max RAM and cores available for for all available nodes would inform users about the max sessions size they can currently launch.