ensure all config items are duplicated on clone/write_config

ensure all config items are duplicated on clone/write_config

Since previously I had found a config item that wasn't being propagated
by lxc-clone, I went through all the config items and made sure that:
 a) Each item is documented in lxc.conf
 b) Each item is written out by write_config

The only one that isn't is lxc.include, which by its nature only pulls
in other config item types.

Signed-off-by: Dwight Engen <dwight.engen@oracle.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>