Add run env variables support (KEY=AVLUE or KEY, will grab the process env value).

No support yet for env files

cli/cmd/run/run.go

@@ -51,6 +51,7 @@ func Command() *cobra.Command {
 	cmd.Flags().BoolVarP(&opts.Detach, "detach", "d", false, "Run container in background and print container ID")
 	cmd.Flags().Float64Var(&opts.Cpus, "cpus", 1., "Number of CPUs")
 	cmd.Flags().VarP(&opts.Memory, "memory", "m", "Memory limit")
+	cmd.Flags().StringArrayVarP(&opts.Environment, "env", "e", []string{}, "Set environment variables")
 
 	return cmd
 }

cli/cmd/run/testdata/run-help.golden

@@ -6,6 +6,7 @@ Usage:
 Flags:
       --cpus float            Number of CPUs (default 1)
   -d, --detach                Run container in background and print container ID
+  -e, --env stringArray       Set environment variables
   -l, --label stringArray     Set meta data on a container
   -m, --memory bytes          Memory limit
       --name string           Assign a name to the container