improve button colors

atdb/taskdatabase/forms.py

atdb/taskdatabase/models.py

...se/templates/taskdatabase/filter/clear_filter_button.html

...atabase/templates/taskdatabase/filter/filter_buttons.html

...askdatabase/templates/taskdatabase/filter/filter_xxx.html

atdb/taskdatabase/templates/taskdatabase/index.html

...database/templates/taskdatabase/quality/quality_page.html

...atabase/templates/taskdatabase/quality/tasks_quality.html

...templates/taskdatabase/quality/tasks_quality_headers.html

atdb/taskdatabase/templates/taskdatabase/query/index.html

.../templates/taskdatabase/query/set_multi_status_panel.html

.../templates/taskdatabase/query/status_buttons_per_row.html

...base/templates/taskdatabase/tasks/set_status_buttons.html

...e/templates/taskdatabase/validation/tasks_validation.html

...tes/taskdatabase/validation/tasks_validation_headers.html

...templates/taskdatabase/validation/validation_buttons.html

...se/templates/taskdatabase/validation/validation_page.html

atdb/taskdatabase/views.py