Stop logging STDOUT and STDERR on every shell out
Stop logging STDOUT and STDERR on every shell out

Sometimes you can log too much. For example, logging a complete
iptables dump on every security group operation, OMG TMI. Doing this
during DSVM run results in a log file >7M compressed. To mitigate this
issue this commit switches the execute method to only log the command
and it's exit code on the success case. If there is a failure the
entire stdin, stdout and stderr are logged.

Change-Id: Iaf17297306dc752e666612033c805a528f078f2f

cloudbase/neutron,mmnelemane/neutron,huntxu/neutron,sasukeh/neutron,dhanunjaya/neutron,igor-toga/local-snat,mattt416/neutron,openstack/neutron,jumpojoy/neutron,MaximNevrov/neutron,dims/neutron,vivekanand1101/neutron,swdream/neutron,chitr/neutron,mahak/neutron,sebrandon1/neutron,igor-toga/local-snat,skyddv/neutron,silenci/neutron,jumpojoy/neutron,asgard-lab/neutron,dhanunjaya/neutron,vivekanand1101/neutron,sasukeh/neutron,MaximNevrov/neutron,klmitch/neutron,openstack/neutron,eayunstack/neutron,glove747/liberty-neutron,shahbazn/neutron,swdream/neutron,shahbazn/neutron,JianyuWang/neutron,sebrandon1/neutron,bigswitch/neutron,glove747/liberty-neutron,apporc/neutron,dims/neutron,yanheven/neutron,noironetworks/neutron,asgard-lab/neutron,bigswitch/neutron,huntxu/neutron,mattt416/neutron,JianyuWang/neutron,skyddv/neutron,wolverineav/neutron,cloudbase/neutron,klmitch/neutron,takeshineshiro/neutron,mahak/neutron,eayunstack/neutron,noironetworks/neutron,wolverineav/neutron,chitr/neutron,mahak/neutron,SamYaple/neutron,apporc/neutron,yanheven/neutron,takeshineshiro/neutron,silenci/neutron,mmnelemane/neutron,SamYaple/neutron,openstack/neutron