Add grub config for iso creation

src/arch/x86_64/grub.cfg

@@ -0,0 +1,21 @@
+# Copyright 2015 Philipp Oppermann
+#
+# 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.
+
+set timeout=0
+set default=0
+
+menuentry "my os" {
+    multiboot2 /boot/kernel-x86_64.bin
+    boot
+}