LXC 2.0.0 beta1 tagged

So you may have noticed I just tagged LXC 2.0.0 beta1.

The current plan is as follow:
- LXC 2.0.0 beta2 next week (28th)
- LXC 2.0.0 rc1 the week after (4th)
- A few more RCs as needed
- Final release around the 18th of January

New features may land until rc1, after that we'll only be taking bugfixes.

As mentioned in the commit message, LXC 2.0 doesn't break backward
compatibility with LXC 1.x, the ABI will be 1.2 and so any existing tool
or binding that was built against LXC 1.0 or LXC 1.1 will keep working
with LXC 2.0.

lxcfs and lxd will also join in the 2.0 fun with lxcfs probably getting
tagged around the same time as lxc and lxd getting tagged in early to
mid February.