unify handling calls in before and after aspects. check method's return value before proceeding with the aspect's actions.
unify handling calls in before and after aspects. check method's return value before proceeding with the aspect's actions.

dreibh/planetlab-lxc-plcapi,dreibh/planetlab-lxc-plcapi,dreibh/planetlab-lxc-plcapi,dreibh/planetlab-lxc-plcapi