Added a version file to revel/cmd

Updated import path detection to make it smarter. You can now use absolute paths etc..

version.go

@@ -0,0 +1,16 @@
+// Copyright (c) 2012-2017 The Revel Framework Authors, All rights reserved.
+// Revel Framework source code and usage is governed by a MIT style
+// license that can be found in the LICENSE file.
+
+package cmd
+
+const (
+	// Version current Revel Command version
+	Version = "0.20.0-dev"
+
+	// BuildDate latest commit/release date
+	BuildDate = "2018-02-06"
+
+	// MinimumGoVersion minimum required Go version for Revel
+	MinimumGoVersion = ">= go1.8"
+)