made INSTALLED_APPS a list so easier to extend in local_settings.py

updated changelog for unreleased changes

Merge pull request #246 from hltcoe/245-add-validators

fixed a style issue

adds migration related to the additional of model validators

Fixes #245 add validators for stricly positive integer fields

Merge pull request #244 from hltcoe/240-date-sort

Merge pull request #243 from hltcoe/remove_abandoned_language

updated the language around open and abandoned assignments to not confuse users

moved abandoned tasks to a table on index page

Merge pull request #239 from hltcoe/new_example_templates

adds documentation to the ner demo

updates ner demo and adds sample data

fixes github workflow for pushing sqlite docker image

ready for next round of development