function _ensureTrailingSlash(fullPath) {
        if (_pathIsFile(fullPath)) {
            return fullPath + "/";
        }
        return fullPath;
    }
Although Brackets is generally standardized on folder paths with a trailing "/", some APIs here
receive project paths without "/" due to legacy preference storage formats, etc.
@param {!string} fullPath  Path that may or may not end in "/"
@return {!string} Path that ends in "/"