Move versioncheck so it happens earlier in the compile process.

cmd/versioncheck.go

@@ -1,6 +0,0 @@
-//+build !go1.5
-
-package cmd
-
-// Upgrade to Go version 1.5 to compile rclone.
-func init() { Go_version_1_5_required_for_compilation() }

fs/versioncheck.go

@@ -0,0 +1,7 @@
+//+build !go1.5
+
+package fs
+
+// Upgrade to Go version 1.5 to compile rclone - latest stable go
+// compiler recommended.
+func init() { Go_version_1_5_required_for_compilation() }