subtitle class: method to process handsontable json

very crude method, simply adds first unique line_id to 'content' field
goal: approximate current update method during the transition
subtitle table: adding button to save data

reload page if data is submitted
future: reload table when data is submitted
subtitle display; disabling handsontable

will re-enable when the 'update' button is made optional in the template.
This entails much refactoring and is, at present, not worth it
subtitle class: method to process handsontable json

loops through table and updates revisions as needed
subtitle class: workaround for char limit

 BadValueError: Indexed value content must be at most 500 characters
Merge remote-tracking branch 'origin/master'