Re-license update_engine to Apache2

This patch automatically replaced the license on all text files from
Chromium OS (BSD style) to AOSP (Apache2), keeping the original year as
a reference.

The license header was added to .gyp and .gypi files, the NOTICE was
replaced with a copy of the Apache2 license and MODULE_LICENSE_* file
was updated.

BUG=b/23084294
TEST=grep 'Chromium OS Authors' doesn't find anything.

Change-Id: Ie5083750755f5180a8a785b24fe67dbf9195cd10
diff --git a/update_engine.gyp b/update_engine.gyp
index 6408593..7bc0ac0 100644
--- a/update_engine.gyp
+++ b/update_engine.gyp
@@ -1,3 +1,18 @@
+#
+# Copyright (C) 2015 The Android Open Source Project
+#
+# 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
+#
+#      http://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.
+#
 {
   'target_defaults': {
     'variables': {