Fixes a bug introduced with commits for OFBIZ-4902.
When you replace the Freemarker if_exists built-in with the ! operator, when the ! is followed by a + you need to evaluate the expression conditioned by the ! 1st. Else the following chars are used as default value. In other words, you need to put parenthesis around the expression including the ! operator
I tested with tomahawk/includes/appbarClose.ftl and header.ftl files of bluelight and droppingcrumbs themes
I then applied the same scheme on catalog/categorydetail.ftl, party/editShoppingList.ftl, ebaystore/store/returnPolicy.ftl and party/findparty.ftl w/o testing. I guess it's ok
I did not find the same scheme elsewhere

git-svn-id: https://svn.apache.org/repos/asf/ofbiz/trunk@1624876 13f79535-47bb-0310-9956-ffa450edef68