Add filter option 'All'

ldvspec/lofardata/static/lofardata/styling/dias.css

ldvspec/lofardata/templates/lofardata/base.html

ldvspec/lofardata/templates/lofardata/index.html

.../templates/lofardata/workspecification/create_update.html

...a/templates/lofardata/workspecification/dataproducts.html

...plates/lofardata/workspecification/dataset_size_info.html

...fardata/templates/lofardata/workspecification/detail.html

...ofardata/templates/lofardata/workspecification/tasks.html