remove `sudo` prefix to upgrade command
remove `sudo` prefix to upgrade command

During testing on hardware, the `sudo` version
of the call to `upgrade.sh` failed silently, even
though `set -e` was included. This is because
the superuser does not have access to the ssh-agent
for the normal user.

heartsucker/securedrop,conorsch/securedrop,chadmiller/securedrop,chadmiller/securedrop,jeann2013/securedrop,GabeIsman/securedrop,kelcecil/securedrop,GabeIsman/securedrop,chadmiller/securedrop,jaseg/securedrop,chadmiller/securedrop,garrettr/securedrop,chadmiller/securedrop,GabeIsman/securedrop,ehartsuyker/securedrop,pwplus/securedrop,jeann2013/securedrop,jeann2013/securedrop,ageis/securedrop,ageis/securedrop,ageis/securedrop,conorsch/securedrop,pwplus/securedrop,micahflee/securedrop,kelcecil/securedrop,kelcecil/securedrop,jrosco/securedrop,jeann2013/securedrop,GabeIsman/securedrop,ehartsuyker/securedrop,jrosco/securedrop,ehartsuyker/securedrop,micahflee/securedrop,heartsucker/securedrop,heartsucker/securedrop,pwplus/securedrop,kelcecil/securedrop,pwplus/securedrop,chadmiller/securedrop,jrosco/securedrop,GabeIsman/securedrop,ehartsuyker/securedrop,pwplus/securedrop,jrosco/securedrop,kelcecil/securedrop,jaseg/securedrop,micahflee/securedrop,heartsucker/securedrop,garrettr/securedrop,garrettr/securedrop,jrosco/securedrop,jaseg/securedrop,jeann2013/securedrop,conorsch/securedrop,ehartsuyker/securedrop,jaseg/securedrop,conorsch/securedrop,jaseg/securedrop,pwplus/securedrop,garrettr/securedrop,micahflee/securedrop,ehartsuyker/securedrop,heartsucker/securedrop,jaseg/securedrop,jrosco/securedrop,ageis/securedrop,GabeIsman/securedrop,jeann2013/securedrop,conorsch/securedrop,kelcecil/securedrop