Simplify versioning.

Author: tintoy

Makefile

@@ -1,3 +1,5 @@
+VERSION = 0.2
+
 default: fmt build test
 
 fmt:
@@ -32,4 +34,4 @@ test: fmt
 	go test -v github.com/DimensionDataResearch/docker-machine-driver-ddcloud/...
 
 version:
-	echo "package main\n\n// DriverVersion is the current version of the CloudControl driver for Docker Machine.\nconst DriverVersion = \"v0.2 (`git rev-parse HEAD`)\"" > ./version-info.go
+	echo "package main\n\n// DriverVersion is the current version of the CloudControl driver for Docker Machine.\nconst DriverVersion = \"v${VERSION} (`git rev-parse HEAD`)\"" > ./version-info.go