add middlebury download script

scripts/download-middlebury.sh

+#/bin/sh -e
+
+if [ $# -eq 0 ]; then
+	echo -e "usage: $0 <target-path>"
+	exit 0;
+fi
+
+path=$1
+
+(
+cd $1
+
+curl -O "https://vision.middlebury.edu/flow/data/comp/zip/other-gray-twoframes.zip"
+curl -O "https://vision.middlebury.edu/flow/data/comp/zip/other-gt-flow.zip"
+unzip "other-gray-twoframes.zip"
+unzip "other-gt-flow.zip"
+cp -r "other-data-gray"/* ./
+cp -r "other-gt-flow"/* ./
+rm -rf "other-data-gray" "other-gray-twoframes.zip"
+rm -rf "other-gt-flow" "other-gt-flow.zip"
+)