Refactoring: rename covid19 to flask_covid19

src/flask_covid19/blueprints/app_admin/app_admin_views.py

.../blueprints/app_admin/templates/app_admin/admin_info.html

...blueprints/app_admin/templates/app_admin/admin_tasks.html

...lates/app_admin/navigation/app_admin_navbar_dropdown.html

src/flask_covid19/blueprints/app_all/all_views.py

...19/blueprints/app_all/templates/app_all/app_all_info.html

...9/blueprints/app_all/templates/app_all/app_all_tasks.html

...lask_covid19/blueprints/app_user/templates/usr/login.html

...sk_covid19/blueprints/app_user/templates/usr/profile.html

..._covid19/blueprints/app_user/templates/usr/user_info.html

...covid19/blueprints/app_user/templates/usr/user_tasks.html

.../app_web/templates/app_application/navigation/navbar.html

...app_web/templates/app_application/navigation/navtabs.html

...ueprints/app_web/templates/app_application/page_home.html

src/flask_covid19/blueprints/app_web/web_views.py

src/flask_covid19/blueprints/data_divi/divi_views.py

...ts/data_divi/templates/divi/country/divi_country_all.html

...ata_divi/templates/divi/country/divi_country_germany.html

...ts/data_divi/templates/divi/country/divi_country_one.html

...lates/divi/country/divi_country_one_cases_cumulative.html