Make Gometalinter Optional
Make Gometalinter Optional

This patch makes Gometalinter optional. Set the environmental variable
GOMETALINTER_DISABLED=1 to disable the gometalinter tool. The target
`gometalinter-all` is still valid whether the tool is disabled or not.

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