add StringUtils to JavascriptClosureAngularClientCodegen.java

Author: wing328

modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/JavascriptClosureAngularClientCodegen.java

@@ -8,6 +8,8 @@
 import java.util.*;
 import java.io.File;
 
+import org.apache.commons.lang.StringUtils;
+
 public class JavascriptClosureAngularClientCodegen extends DefaultCodegen implements CodegenConfig {
     public JavascriptClosureAngularClientCodegen() {
         super();