As stated in the related commit message:

> As lxc-docker's development is still in progress and it hasn't settled
down to a solid and fixed feature set yet, it makes more sense to stick
with the bleeding edge for now.
It might make sense to use 'present' instead of 'latest' once lxc-docker
has matured a bit more.

What do you think? Otherwise, people will end up with really outdated Docker versions.
If you still think, keeping `present` is better, I'll revert accordingly.

@garethr What do you think?