l10n: update messages.pot with newest strings
l10n: update messages.pot with newest strings

./manage.py translate --extract-update

ehartsuyker/securedrop,heartsucker/securedrop,conorsch/securedrop,heartsucker/securedrop,conorsch/securedrop,heartsucker/securedrop,heartsucker/securedrop,garrettr/securedrop,conorsch/securedrop,garrettr/securedrop,conorsch/securedrop,conorsch/securedrop,ehartsuyker/securedrop,garrettr/securedrop,garrettr/securedrop,heartsucker/securedrop,ehartsuyker/securedrop,ehartsuyker/securedrop,ehartsuyker/securedrop,ehartsuyker/securedrop