Support environment vars (#155)

* updage flag values from environment variables

* add log and removing unused constants

* removing unused code

* Docker build client

* fix indentation

* Documentation with docker command

* use docker volume

client/cmd/up.go

@@ -21,7 +21,7 @@ var (
 		Use:   "up",
 		Short: "install, login and start wiretrustee client",
 		RunE: func(cmd *cobra.Command, args []string) error {
-
+			SetFlagsFromEnvVars()
 			err := loginCmd.RunE(cmd, args)
 			if err != nil {
 				return err