snapshot: support ip address literals, more docs - #403

control: job dependencies complete; ready to run (waiting for 13 m 29 s)
control: job assigned to worker 01M4WACFK2B4T8N1V6DG847HPA [factory aws, i-0a24c170391cb6089] (queued for 24 s)
...
task: starting task 0: "setup"
...
| No VM guests are running outdated hypervisor (qemu) binaries on this host.
| + groupadd -g 12345 build
| + useradd -u 12345 -g build -d /home/build -s /bin/bash -c build build
| + echo 'build ALL=(ALL:ALL) NOPASSWD:ALL'
| + chmod 0440 /etc/sudoers.d/build
| + cat
| + chmod 0755 /bin/pfexec
| + cat
| + chmod 0755 /bin/ptime
| + [[ ! -L /bin ]]
| + mkdir -p /work
| + mkdir -p /home/build
| + chown build:build /home/build /work
| + chmod 0700 /home/build /work
task: process exited: duration 18675 ms, exit code 0
task: starting task 1: "authentication"
task: process exited: duration 4 ms, exit code 0
task: starting task 2: "build"
task: process exited: duration 0 ms, exit code 0
|W| found 0 output files