Add proper license headers for upstreaming

Add missing Apache license headers.

Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
Change-Id: Ic53d21b8121005037ac5acfde23ddbe23a9b9f44
diff --git a/cmd/lkml/main.go b/cmd/lkml/main.go
index 0711f0b..f3dae41 100644
--- a/cmd/lkml/main.go
+++ b/cmd/lkml/main.go
@@ -1,3 +1,17 @@
+// Copyright 2019 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 package main
 
 import (
diff --git a/lkml/lkml.go b/lkml/lkml.go
index 0645bd5..43b3b74 100644
--- a/lkml/lkml.go
+++ b/lkml/lkml.go
@@ -1,3 +1,17 @@
+// Copyright 2019 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 // Package lkml provides a controller which processes strings received
 // containing mailing list patches, applies them to specified repo,
 // and triggers ProwJobs.