fixed type of convert() return for values < 1KB (#985)
fixed type of convert() return for values < 1KB (#985)

Fixes #972

When the value (e.g. of UsedSize) was < 1KB, the convert returned int instead of str
and that broke the logic of CLI table size estimate
shuklanirdesh82/docker-volume-vsphere,luomiao/docker-volume-vsphere,govint/docker-volume-vsphere,shuklanirdesh82/docker-volume-vsphere,venilnoronha/docker-volume-vsphere,brunotm/docker-volume-vsphere,ashahi1/docker-volume-vsphere,luomiao/docker-volume-vsphere,brunotm/docker-volume-vsphere,govint/docker-volume-vsphere,venilnoronha/docker-volume-vsphere,govint/docker-volume-vsphere,lipingxue/docker-volume-vsphere,lipingxue/docker-volume-vsphere,brunotm/docker-volume-vsphere,venilnoronha/docker-volume-vsphere,shuklanirdesh82/docker-volume-vsphere,pshahzeb/vsphere-storage-for-docker,shuklanirdesh82/docker-volume-vsphere,brunotm/docker-volume-vsphere,shivanshu21/docker-volume-vsphere,venilnoronha/docker-volume-vsphere,lipingxue/docker-volume-vsphere,venilnoronha/docker-volume-vsphere,shivanshu21/docker-volume-vsphere,pshahzeb/vsphere-storage-for-docker,ashahi1/docker-volume-vsphere,lipingxue/docker-volume-vsphere,luomiao/docker-volume-vsphere,shivanshu21/docker-volume-vsphere,shuklanirdesh82/docker-volume-vsphere,shuklanirdesh82/docker-volume-vsphere,pshahzeb/vsphere-storage-for-docker,brunotm/docker-volume-vsphere,shivanshu21/docker-volume-vsphere,ashahi1/docker-volume-vsphere,shivanshu21/docker-volume-vsphere,govint/docker-volume-vsphere,lipingxue/docker-volume-vsphere,govint/docker-volume-vsphere,ashahi1/docker-volume-vsphere,shivanshu21/docker-volume-vsphere,ashahi1/docker-volume-vsphere,pshahzeb/vsphere-storage-for-docker,lipingxue/docker-volume-vsphere,ashahi1/docker-volume-vsphere,pshahzeb/vsphere-storage-for-docker,luomiao/docker-volume-vsphere,venilnoronha/docker-volume-vsphere,luomiao/docker-volume-vsphere,pshahzeb/vsphere-storage-for-docker,brunotm/docker-volume-vsphere,luomiao/docker-volume-vsphere,govint/docker-volume-vsphere