Switch to free icons. Make admin menu icons larger (same size as user)

portal/templates/portal/public/base.html

portal/templates/portal/secure/admin/base.html

portal/templates/portal/secure/admin/delete.html

portal/templates/portal/secure/user/base.html

portal/templates/portal/secure/user/datafile_list.html

portal/templates/portal/secure/user/delete.html

portal/templates/portal/secure/user/list.html

portal/views/secure/datafile.py

portal/views/secure/dataset.py