Support trusty; pre-release support for utopic

- Remove the "prerelease" tag for trusty
- Add preliminary support for utopic
Update PXE install logic

pxe-install-flag was being abused to check both for unattended
installs and cluster installs.  In preparation for debconf support,
define variables for unattended installs (regardless of metapackage)
and set the category variable earlier.

Similarly, "cluster" was being abused to mean "unattended".  This
de-couples the metapackage from the installation method.
Further noninteractive enhancements

Ensure that the msmtp-mta prompt is only displayed for
interactive installs, and that the defaults are sane.
Don't display "continue" prompt when unattended

- Ensure the "continue" prompt is suppressed for all unattended installs
  not just cluster unattended
Remove legacy cluster network-fixup code

Now that all stage2 installs require a working network at boot, there
is no need to "fixup" the ifupdown config that netcfg generates.

The installer really shouldn't muck with anything on disk.  Networking
stuff specific to PXE installs should be handled in the postinstall
script, if we ever need to do this in the future.
Add "cmdline" query to athinfod

Add a query to the installer athinfod to display /proc/cmdline
installer subdir has moved to its own repo

Nuke the installer/ sub-directory, it has moved to its own repository
Switch to qemu from vmware; enhance tests

- VMware didn't do as well headless as I would have liked, and ESX
  was a bit too large of a hammer, so we switch to QEMU.
- Change the logic to simply bootstrap the stage2 installer rather
  then writing out our own preseed.
- Log to a uniquely generated log file
- Break testing out into 3 stages (networking, installer,
  final working machine).
Add a crontab and wrapper script

- Check in a copy of the crontab in use and the wrapper script
  used to test all 3 cluster machine types.