Changes the license of Makefile to APL2.

  Because the upstream (https://github.com/mkouhei/makefile-go) has changed.

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>

Makefile

@@ -1,20 +1,19 @@
 #!/usr/bin/make -f
 # -*- makefile -*-
-# Copyright (C) 2015 Kouhei Maeda <mkouhei@palmtb.net>
 #
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
+# Copyright 2015 Kouhei Maeda <mkouhei@palmtb.net>
 #
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the
-# GNU General Public License for more details.
+# 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
 #
-# You should have received a copy of the GNU General Public License
-# along with this program.	 If not, see <http://www.gnu.org/licenses/>.
-
+#	  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.
 
 REPO := $(shell git config remote.origin.url)