add license file (Apache 2.0 as in metadata)

LICENSE

@@ -0,0 +1,13 @@
+Copyright (c) 2017: Dominic Orchard, Vilem-Benjamin Liepelt, Harry Clarke
+
+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.

reprinter.cabal

@@ -4,7 +4,7 @@ cabal-version: 1.12
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 164cc4d2149c1ec8f25483d408c9daf06fa85d19cdf998cc487e76a9c03c3efe
+-- hash: b19671665da6cf09b8aa157c387db536e02e3f8518551ed0fcfd6c5c43b40134
 
 name:           reprinter
 version:        0.3.0.0
@@ -16,6 +16,7 @@ bug-reports:    https://github.com/camfort/reprinter/issues
 author:         Dominic Orchard, Vilem-Benjamin Liepelt, Harry Clarke
 maintainer:     [email protected]
 license:        Apache-2.0
+license-file:   LICENSE
 build-type:     Simple
 extra-source-files:
     CHANGELOG.md