add unhandled exception logging
add unhandled exception logging

citrix-openstack/build-swift3,citrix-openstack-build/swift3,swiftstack/swift3-stackforge,citrix-openstack/build-swift3,citrix-openstack-build/swift3,tumf/swift3,Zentyal/zentyal-swift-middleware,KoreaCloudObjectStorage/swift3,tumf/swift3,KoreaCloudObjectStorage/swift3,Zentyal/zentyal-swift-middleware,stackforge/swift3,stackforge/swift3,swiftstack/swift3-stackforge