Fixes scope problems in docker volume driver
Fixes scope problems in docker volume driver

The introduction of gofig with scoping caused the values that
were customizable for the docker driver to not work anymore.  This
commit brings that functionality where scoped docker parameters
can be included now in modules and generally.

akutz/rexray,cduchesne/rexray,akutz/rexray,emccode/rexray,codedellemc/rexray,thecodeteam/rexray,akutz/rexray,akutz/rexray,codedellemc/rexray,codedellemc/rexray,codedellemc/rexray,oppodeldoc/rexray,oppodeldoc/rexray,thecodeteam/rexray,cduchesne/rexray,thecodeteam/rexray,cduchesne/rexray,oppodeldoc/rexray,oppodeldoc/rexray,emccode/rexray,akutz/rexray,thecodeteam/rexray,codedellemc/rexray,thecodeteam/rexray,akutz/rexray,cduchesne/rexray,emccode/rexray,emccode/rexray,cduchesne/rexray,thecodeteam/rexray,oppodeldoc/rexray,cduchesne/rexray,codedellemc/rexray,oppodeldoc/rexray