Restarting the process of creating a unit types table.  Added in the scaffolding for a unit types table.
Finally got the parent_id to show up when adding in a sub-unit type below another unit.  Will clean up in subsequent commits.
Finished work on the unit types section, added capability to chain unit types together and the views to be able to navigate through them.
Added in the ability to select a unit type when creating a new processing unit.  The selection of a unit type in this instance is an aggregated string, should be improved upon at a later date.  There were also methods added to the unit_type controller to accomplish the aggregation of unit type information.
Added in the functionality to assign an aggregated unit type string to a unit type id, then assign that unit type id to the processing unit you're selecting it for.
Merged in changes between the ancestry_reset_work branch and the master branch