Added method for calculating max_height of a hierarchy in a hierarchy field.  This is going to be used for Issue #608.
Renamed collect to map for consistency
Solved Issue #608: Added a column for each level of the hierarchy in collection's the CSV. Pending: refactoring
Refactor: Moved functionality to subclasses.
Added cache_for_read  for improving performance
Rescue when calling ancestors because the values stored in ES can be invalid and  ascendants_of_in_hierarchy raise an exception if the parameter is invalid
ascendants for hierarchy fields was not returning the same when cache_for_read was on
Fixed performance issues on the implementation of Issue #608
Reversed ancestors list in order for high level hierarchy elements to be at the same column( Issue #608)
Make ancestors only work for id. It was not being used anywhere else
Replaced ids by names in the CSV new columns for hierarchies. Closes #608
Fixes #747 extra hierarchy columns are marked as ignore in wizard import