pkg/licenses: add license generation code.

Autogenerates licenses.go file to append all license files from
the 'vendor' directory. Resolves #11

LICENSE

@@ -1,4 +1,4 @@
- Apache License
+                                 Apache License
                            Version 2.0, January 2004
                         http://www.apache.org/licenses/
 

pkg/licenses/generate.go

@@ -0,0 +1,16 @@
+// Copyright 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"). You may
+// not use this file except in compliance with the License. A copy of the
+// License is located at
+//
+//     http://aws.amazon.com/apache2.0/
+//
+// or in the "license" file accompanying this file. This file 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 licenses
+
+//go:generate ../../scripts/licenses.sh license.go