PARQUET-1140: Fail on RAT errors in CI

Author: Korn, Uwe <Uwe.Korn@blue-yonder.com>

Closes #413 from xhochy/PARQUET-1140 and squashes the following commits:

5ae89dc [Korn, Uwe] Add license headers to Snappy related files
0d17129 [Korn, Uwe] PARQUET-1140: Fail on RAT errors in CI
diff --git a/ci/travis_script_cpp.sh b/ci/travis_script_cpp.sh
index 78d7d86..d3cef66 100755
--- a/ci/travis_script_cpp.sh
+++ b/ci/travis_script_cpp.sh
@@ -17,8 +17,10 @@
 : ${CPP_BUILD_DIR=$TRAVIS_BUILD_DIR/parquet-build}
 
 # Check licenses according to Apache policy
-git archive HEAD -o parquet-cpp-src.tar.gz "--remote=file://$TRAVIS_BUILD_DIR"
+pushd $TRAVIS_BUILD_DIR
+git archive HEAD -o parquet-cpp-src.tar.gz
 $TRAVIS_BUILD_DIR/dev/release/run-rat.sh parquet-cpp-src.tar.gz
+popd
 
 pushd $CPP_BUILD_DIR
 
diff --git a/cmake_modules/SnappyCMakeLists.txt b/cmake_modules/SnappyCMakeLists.txt
index 202d063..0348eb1 100644
--- a/cmake_modules/SnappyCMakeLists.txt
+++ b/cmake_modules/SnappyCMakeLists.txt
@@ -1,3 +1,17 @@
+# 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.
+#
+# Originally import from the Snappy repository with the following license:
+#
 # Copyright 2008 Google Inc. All Rights Reserved.
 #
 # Redistribution and use in source and binary forms, with or without
@@ -82,4 +96,4 @@
 install(TARGETS snappy snappystatic
   RUNTIME DESTINATION bin
   LIBRARY DESTINATION lib
-  ARCHIVE DESTINATION lib)
\ No newline at end of file
+  ARCHIVE DESTINATION lib)
diff --git a/cmake_modules/SnappyConfig.h b/cmake_modules/SnappyConfig.h
index 74eb776..5764deb 100644
--- a/cmake_modules/SnappyConfig.h
+++ b/cmake_modules/SnappyConfig.h
@@ -1,3 +1,22 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you 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.
+//
+// Originally import from the Snappy repository with the following license:
+//
 // Copyright 2008 Google Inc. All Rights Reserved.
 //
 // Redistribution and use in source and binary forms, with or without