Minor: set file mode explicitly so corda.jar is executable on UNIX when copying from a downloaded jar

gradle-plugins/cordformation/src/main/groovy/net/corda/plugins/Node.groovy

@@ -172,6 +172,7 @@ class Node {
             from cordaJar
             into nodeDir
             rename cordaJar.name, NODEJAR_NAME
+            fileMode 0755
         }
     }