We've updated to Xcode 8 and using the plugin we do this:
add "-archivePath "${WORKSPACE}/build/xxxxx.xcarchive" to the Custom Xcode Build Arguments
then in a shell step following the xocde step NOTE: this uses the ad-hoc cert, you would want your "distribution" there (I think):
#
# warning: PackageApplication is deprecated, use `xcodebuild -exportArchive` instead.
#
# for this command we need a very simple Plist file. created here
#
#!/bin/bash
cat <<EOF > ./build/export.plist
<?xml version="1.0" encoding="UTF-8"?>
<plist version="1.0">
<dict>
<key>method</key>
<string>ad-hoc</string>
</dict>
</plist>
EOF
xcodebuild -exportArchive -archivePath build/xxxxx.xcarchive -exportOptionsPlist build/export.plist -exportPath .