Initial support for building Yosemite guests

- In addition to growing BaseSystem and copying over Packages, we
  also copy the BaseSystem dmg and chunklist files to the root
  of this new grown BaseSystem (yes, a copy of its original at the
  root of itself).
  - My guess would be that this is so that the installer can use
    these to do recovery partition-related tasks, verification, etc.
    because without it, the installer would fail complaining that
    it could not verify the recovery partition.
  - Cribbed from the 'convert_mavericks_image' script from
    Parallels 10 - a much simpler approach than VMware Fusion's
    approach of setting up a second disk with a custom boot config.
- Fixes #17.
pkg postinstall ssh enable: new launchd overrides path on 10.10
Update README.md
Rename user variables.
Set parallels tools path dynamically.
Remove unused kcpassword file.
Document set_kcpassword.py.
Merge branch 'master' into easier-renaming-of-vagrant-user

Conflicts:
	prepare_iso/support/pkg-postinstall
Default autologin to false.
Document prepare_iso.sh switches.
Document new packer variables.
Merge pull request #23 from newspaperclub/easier-renaming-of-vagrant-user

Move vagrant user's username into variables.
Use variable for PlistBuddy path
Fix missing expansion for admin groupmembers attr
Set LastSeenCloudProductVersion depending on OS ver
Quote USER_UID to make shellcheck happy
Skip the diagnostics & usage prompt if on Yosemite
Merge branch 'master' into newspaperclub-templates