test to see if metaClass properties are corbOptions first

In more recent versions of Gradle, some of the properties, such as "argsString" and "validators" throw exceptions. We can avoid that by ensuring that the property name is a corbOption and only acecssing the property object if it is.

resolves issue 373

Author: hansenmc

src/main/groovy/com/marklogic/gradle/task/CorbTask.groovy

@@ -153,11 +153,11 @@ XQUERY-MODULE".tokenize(',')
     this.metaClass.getProperties().collectEntries {
       String corbOptionKey = CORB_PROPERTY_PREFIX + it.name.capitalize()
       //evaluate whether a value is set and the name matches the corbOptions key pattern
-      if (this[it.name] && corbOptions[corbOptionKey]) {
-        [(corbOptions[corbOptionKey]): this[it.name] ]
-      } else {
-        [:]
-      }
+	  if (corbOptions[corbOptionKey] && this[it.name]) {
+	    [(corbOptions[corbOptionKey]): this[it.name] ]
+	  } else {
+	    [:]
+	  }
     }
   }