autoinstall: add jessie-installer

This adds a profile for Debian 8, codenamed Jessie. This is identical
with precise/trusty, with the following differences:
- s/ubuntu-installer/debian-installer
- no biosdevname=0, since that's biosdevname is Ubuntu-only
  functionality (and >= trusty as well).

Note that this won't make jessie installs working by themselves. More
changes are needed and will follow this commit.

Change-Id: I4bfec1ea14400208d300af96e0bc223ccb1872ec