Handle N/A float types for cli fallbacks

[abhinavDhulipala]

"Failed to parse node metrics: sinfo failed to parse line 0: {\"s\": \"completing\", \"mem\": 770000, \"n\": \"cs156\", \"l\": N/A, \"p\": \"hw\", \"fmem\": N/A, \"cstate\": \"56/8/0/64\", \"w\": 1}" 

Nodes that are in a completing state emit N/A as free mem and cpu load. Our parser needs to handle that