BUG 9180 can't search string without fieldname

Error
-----
can't search string without fieldname only fields are searched

Solution
--------
correct identification of field name to allow the search using plain string
in processname, status fields.

workflow/engine/classes/class.AppSolr.php

@@ -728,7 +728,7 @@ class AppSolr
       $searchText = strstr ($tok, ":");
       
       // verify if there's a field definition
-      if ($fieldName === false) {
+      if ($fieldName === false || $fieldName == "") {
         // it's not a field
         // the token is not a field
         // add it completelly