SPARK-5308 [BUILD] MD5 / SHA1 hash format doesn't match standard Maven output

Here's one way to make the hashes match what Maven's plugins would create. It takes a little extra footwork since OS X doesn't have the same command line tools. An alternative is just to make Maven output these of course - would that be better? I ask in case there is a reason I'm missing, like, we need to hash files that Maven doesn't build.

Author: Sean Owen <sowen@cloudera.com>

Closes #4161 from srowen/SPARK-5308 and squashes the following commits:

70d09d0 [Sean Owen] Use $(...) syntax
e25eff8 [Sean Owen] Generate MD5, SHA1 hashes in a format like Maven's plugin

dev/create-release/create-release.sh

@@ -122,8 +122,14 @@ if [[ ! "$@" =~ --package-only ]]; then
   for file in $(find . -type f)
   do
     echo $GPG_PASSPHRASE | gpg --passphrase-fd 0 --output $file.asc --detach-sig --armour $file;
-    gpg --print-md MD5 $file > $file.md5;
-    gpg --print-md SHA1 $file > $file.sha1
+    if [ $(command -v md5) ]; then
+      # Available on OS X; -q to keep only hash
+      md5 -q $file > $file.md5
+    else
+      # Available on Linux; cut to keep only hash
+      md5sum $file | cut -f1 -d' ' > $file.md5
+    fi
+    shasum -a 1 $file | cut -f1 -d' ' > $file.sha1
   done
 
   nexus_upload=$NEXUS_ROOT/deployByRepositoryId/$staged_repo_id