ransake working in a limited manner
further ransack functionality added, with user selectable fields. Need to see how to limit the search fields available to the user, as they currently have access to all of them
added method to user model to limit the fields searchable through ransack advanced search. This is achieved using an UNTRACKABLE_ATTRIBUTES array to list those columns that are not part of the drop down list
added CONSTANT = hash for ransack predicates to limit the list available to users for search
limited predicate list to: contains, starts with, matches and equals. Search appears to be working
changes from merge with ransack branch