Add basic import/export capability about mdeditor HOT 2 OPEN

Work on this issue is here: https://github.com/jlblcc/mdEditor/tree/feature-45-import-export

Preview here: https://jlblcc.github.io/mdEditor/#/import

Currently, you can save all data in a single json file and then import the file. On import, the records are listed and may be (de)selected for import. There is also the option to merge or replace records. The import will only select JSON files. The files are validated to make sure they are actually valid JSON and conform to the JSON API schema (which is the format the mdEditor exports).

Not sure we need the zip archive support.

We will need the single file(mdJSON) export/import. The idea is to handle it the same way on import (the preview will only list a single record). Also, if a mdJSON record is imported the contacts referenced by that record will be imported by default to maintain referential integrity, regardless of whether they are selected or not.

from mdeditor.

Most of this was implemented in #48. Still need to implement the file selection for export.

from mdeditor.