Ubuntu Support

This release adds Ubuntu support, supporting ZFS builds based on the headers, modules, and source-specific packages pulled via 'apt'.

As of this release, you will need to pass the full 'uname -a' string, as that is the only way to generically determine distros like Ubuntu - there is not enough information available in the 'uname -r' release.

Initial Release

This is the initial release of the ZFS builder. It supports building ZFS userland and kernel, with distro-specific mechanisms to pull kernel source for linuxkit.