fixed issue preventing update image when doing wdtModelOnly (#184)

Author: ddsharpe

imagetool/src/main/java/com/oracle/weblogic/imagetool/cli/menu/UpdateImage.java

@@ -67,7 +67,7 @@ public CommandResponse call() throws Exception {
             }
             dockerfileOptions.setOracleHome(oracleHome);
 
-            if (wdtOptions.isUsingWdt()) {
+            if (wdtOptions.isUsingWdt() && !wdtOptions.modelOnly()) {
                 String domainHome = baseImageProperties.getProperty("DOMAIN_HOME", null);
                 if (domainHome == null && wdtOperation == WdtOperation.UPDATE) {
                     return new CommandResponse(-1, "IMG-0071", fromImage);

imagetool/src/main/java/com/oracle/weblogic/imagetool/cli/menu/WdtOptions.java

@@ -35,6 +35,15 @@ boolean isUsingWdt() {
         return wdtModelPath != null || wdtArchivePath != null;
     }
 
+    /**
+     * Return true if the user specified the wdtModelOnly option, and
+     * WDT should not run a create or update script.
+     * @return true if the WDT script should not run during the build.
+     */
+    boolean modelOnly() {
+        return wdtModelOnly;
+    }
+
     /**
      * Checks whether the user requested a domain to be created with WDT.
      * If so,  creates required file links to pass the model, archive, variables file to build process.