confirmed and at_time mutually exclusive
confirmed and at_time mutually exclusive

Added in error checking to make sure that an error is kicked back when
the user sends both commit confirmed and commit at. Junos cannot accept
both of these on the same commit.

aitorhh/ncclient,kroustou/ncclient,ncclient/ncclient,nnakamot/ncclient,lightlu/ncclient,nwautomator/ncclient,leopoul/ncclient,joysboy/ncclient,einarnn/ncclient,GIC-de/ncclient,earies/ncclient,cmoberg/ncclient,vnitinv/ncclient,OpenClovis/ncclient