Add license headers and other cleanup

pkg/storage/storage_errors.go

@@ -0,0 +1,21 @@
+package storage
+
+type GenericError struct {
+	bucket string
+	path   string
+}
+
+type ObjectExists struct {
+	bucket string
+	key    string
+}
+
+type ObjectNotFound GenericError
+
+func (self ObjectNotFound) Error() string {
+	return "Not Found: " + self.bucket + "#" + self.path
+}
+
+func (self ObjectExists) Error() string {
+	return "Object exists: " + self.bucket + "#" + self.key
+}