fail to install maas-dhcp in a container

As we can see from bug 978297.
In precise, apparmor doesn't start in a container.
So in debian/maas-dhcp.postinst and debian/maas-dhcp.postinst, we should
not call the apparmor_parser command in a container.

/bin/running-in-container is used in /etc/init.d/apparmor to find out if it is running in a container.
ubuntu@ubuntu-lxc-virtual-maas-0:~$ dpkg -S /bin/running-in-container
upstart: /bin/running-in-container

install log

2013-07-03 14:24:28,334 unit:virtual-maas/0: hook.output INFO: Setting up maas-dhcp (1.2+bzr1373+dfsg-0ubuntu1~12.04.1) ...
2013-07-03 14:24:29,614 unit:virtual-maas/0: hook.output ERROR: Unable to open /sys/kernel/security/apparmor/.replace - Permission denied
2013-07-03 14:24:29,616 unit:virtual-maas/0: hook.output ERROR: apparmor_parser: Unable to replace "/usr/sbin/dhcpd".
2013-07-03 14:24:29,617 unit:virtual-maas/0: hook.output ERROR: Permission denied; attempted to load a profile while confined?
2013-07-03 14:24:29,623 unit:virtual-maas/0: hook.output ERROR: Warning failed to create cache: usr.sbin.dhcpd
2013-07-03 14:24:29,631 unit:virtual-maas/0: hook.output INFO: Setting up python-bson-ext (2.2-4~cloud0) ...
2013-07-03 14:24:29,641 unit:virtual-maas/0: hook.output ERROR: dpkg: error processing maas-dhcp (--configure):
 subprocess installed post-installation script returned error exit status 234
dpkg: dependency problems prevent configuration of maas-dns:
 maas-dns depends on maas-dhcp (= 1.2+bzr1373+dfsg-0ubuntu1~12.04.1); however:
  Package maas-dhcp is not configured yet.
dpkg: error processing maas-dns (--configure):
 dependency problems - leaving unconfigured