Add missing license headers

Found with:
  for f in $(find [a-z]* -name \*.java); do echo "$f $(head -n1 $f)"; done | grep -v '// Copyright'

The remaining classes not touched in this file all have nonstandard
license headers, because they were copied from other projects. Or
they're plugins, which should be fixed separately.

Copyright dates are taken from original creation of the file.

Change-Id: I3be07ac46fd999f07c230eacbf4508f39fda1b77

java/com/google/gerrit/server/securestore/SecureStoreClassName.java

@@ -1,3 +1,17 @@
+// Copyright (C) 2014 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.
+
 package com.google.gerrit.server.securestore;
 
 import static java.lang.annotation.RetentionPolicy.RUNTIME;