add a stat(file) shortcut

Signed-off-by: Jeff Carr <jcarr@wit.com>

unix.go

@@ -212,6 +212,15 @@ func IsDirectory(path string) bool {
 	return info.IsDir()
 }
 
+// returns true if the file exists
+func Exists(file string) bool {
+	_, err := os.Stat(file)
+	if err != nil {
+		return false
+	}
+	return true
+}
+
 func VerifyLocalGoRepo(gorepo string) bool {
 	// Get current user
 	usr, err := user.Current()