Implemented a first version of the to_string method for JSON fragment

First working version of the new Plan details form

Fixed ethical_issue name in structured answer

Added classname to the schema form

Moved maDMP code from the roadmap codebase to the OPIDoR codebase

Merge branch 'dev' into feature/save_dmpdata_as_json

Removed schema presence validation for now

Updated fragment models according to data model

Multiple changes to Project & Meta fragments are saved ...

Persons fragments should be created only when they don't exist

Fixed project fragment generation when creating a plan

References to children fragment should be updated when creating or deleting a child fragment

Destroying a research output should destroy the associated json_fragment

Merge branch 'fix/seed' into dev

Added missing saving status for structured answers

STI column value should be more readable

Fixed issue with seed file

Plan details & Research Outputs are now saved as JSON fragments

Updated StructuredAnswer model with new columns

Update fragments models with new table columns

Updated fragments models comments

Implemented JSON fragments models methods according to the class model

Removed parent_id column

Merge remote-tracking branch 'origin/dev' into feature/schema_to_models

(WIP) Implemented structured schema into rails models

Renamed object column to classname in structured_data_schema table

Deactivated schema field validation for now

Added Schema update, create & delete forms

Added JSON schemas list for super admin

Added form-control CSS class on dynamic form fields

Fixed question display in dynamic forms