Use longs for int64 values

[jimmidyson]

Json schema doesn't support long, just integer & number. As an example, resource.Quantity had to be a long to accept memory in bytes.

See fabric8io/elasticsearch-cloud-kubernetes#9

[jimmidyson]

Actually looking at resource/Quantity show that it should be marshalled to/from a string as it contains format in the string. Easiest would be to just use string for now but will need to revisit it later when we have a ui for editing stuff like memory.