make lxcapi_get_interfaces and lxcapi_get_ips unprivileged container aware

Based on Stéphane's suggestion, those two API methods now;

* fork a new process,
* switch to appropriate namespace(s),
* do what we want,
* return the data over a pipe to the parent which returns the result to the original caller.

For the whole thread please see;

 https://lists.linuxcontainers.org/pipermail/lxc-devel/2014-January/007362.html

This patch also makes lxc-ls and lxc-info call those functions.

I'm adding Stéphane as an author here since both the idea as well as
the initial setns code come from him.

Author: S.Çağlar Onur <caglar@10ur.org>
Author: Stéphane Graber <stgraber@ubuntu.com>
Signed-off-by: S.Çağlar Onur <caglar@10ur.org>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Update Fedora and CentOS templates for common conf includes.

This updates the Fedora and CentOS templates to utilize a common
included config.  This is largely based on the changes in the Oracle
template with some exceptions.

Dropping of setpcap (present in the Oracle template) is commented out in
the Fedora template.  It seems to cause problems, such as large login
delays with Fedora 20 containers (but not Fedora 19 - strange).

The Fedora template is further modified to disable systemd-journald.service
as it is unnecessary in a container and causes serious problems when
running in a Fedora 20 container.

The Fedora template is also updated to default to Fedora 20 when running
on a non-Fedora host.

Regards,
Mike

Signed-off-by: Michael H. Warfield <mhw@WittsEnd.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>