A fresh cloud image's apt cache is stale/effectively empty — installing
snmpd without an apt-get update first could fail outright or hang on
unreachable mirrors, and the install call wasn't guarded, so a timeout
propagated as an opaque unguarded exception instead of a clean failure
result.
Also adds a new apt_update_upgrade device action (apt-get update +
upgrade), used by netork's VM-provisioning bootstrap alongside the
existing fix_apt_proxy action to fully prep a freshly provisioned VM's
apt before installing anything on it.
Christian Manivong
8436013dcd