use different log categories in commands

use different log categories in commands

lxc_<cmd>.c and <cmd>.c files use the same log category : lxc_<cmd>.
The symbol is multiply defined and linking statically lxc commands is
not possible.

The patch introduces new log categories with a '_ui' suffix to
differentiate the command line interface from the library routine.

Reported-by: Ciprian Dorin, Craciun <ciprian.craciun@gmail.com>
Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>