builder: Add the logo to the HTML manual page.

Unfortunately:

 - It appears below the TOC.  This is unavoidable because of the
   flow of the current HTML.

 - The logo is now duplicated in git.
builder: Add more templates to the list which is copied to the website.
builder: Kill any daemons started by installed packages.

Some --install requests may pull in packages that start daemons (dbus
being a favourite daemon apparently).  These daemons will prevent the
disks from being unmounted and everything being cleaned up at the end.
Add some experimental code to kill these daemons.