lxc-start-ephemeral: Allow unprivileged run

This allows running lxc-start-ephemeral using overlayfs. aufs remains
blocked as it hasn't been looked at and patched to work in the kernel at
this point (not sure if it ever wil).

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
travis: Drop workaround introduced last week

Travis has now corrected the bug in their build environment so we no
longer need to force the autogen script through bash.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
coverity: Free bdev in clone_update_rootfs

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
coverity: Check return value of fcntl in lxc_popen

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
coverity: Always check mkdir_p's return value

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
coverity: check return value of fcntl in usernsexec

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
coverity: Don't store fgets return value if we don't use it

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
coverity: Drop dead code

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
coverity: Check return value from open

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
bdev: Add aufs support

This is pretty much copy/paste from overlayfs.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>