Fix default RSpec version to be a string.
Fix default RSpec version to be a string.

The AM API spec says that the version is a string. Make the '-t'
command line option default to '3' (string) instead of 3 (int).

tcmitchell/geni-tools,GENI-NSF/gram,tcmitchell/geni-tools,GENI-NSF/gram,ahelsing/geni-tools,plantigrade/geni-tools,plantigrade/geni-tools,ahelsing/geni-tools,GENI-NSF/gram