fix #1326 extend a length of label value

src/main/java/org/codelibs/fess/app/web/admin/labeltype/CreateForm.java

@@ -41,7 +41,7 @@ public class CreateForm {
     public String name;
 
     @Required
-    @Size(max = 20)
+    @Size(max = 100)
     @Pattern(regexp = "^[a-zA-Z0-9_]+$")
     public String value;