Add missing NOTICE file

Author: José Valim

NOTICE

@@ -0,0 +1,22 @@
+LEGAL NOTICE INFORMATION
+------------------------
+
+All the files in this distribution are copyright (c) 2012 Plataformatec
+covered under Elixir's license (see the file LICENSE) except the cases
+below.
+
+== lib/elixir/src/elixir_parser.erl (generated by build scripts)
+
+Copyright Ericsson AB 1996-2015
+
+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.