Fixes/features for OSX builds

Updated to latest jarbundler version (2.2.0)
Keep exec permissions on java stub when copying (use ant.exec instead of ant.copy)
Resources placed in <project root>/resources/build will be copied to Content/Resources when creating bundle
Add JVM options & properties to Info.plist automatically - must define in BuildConfig.groovy as follows:
griffon{
     app{
          jarbundler{
               //space-separated string of jvm options
               jvmOpts = "-Xms1g -Xms2g"
               //string key-value pairs: equivalent of -Dkey=value
               jvmProps = ["key1":"value1", "key2":"value2", "key3":"true"]
          }
     }
}