Show image name in 'not found' error for launch
Show image name in 'not found' error for launch

When you forget to include an image name in 'lxc launch', it's nice to
see the name of the image that wasn't found, to jog your memory that
there probably isn't an image named 'testcontainer' or whatever.

Signed-off-by: Michael McCracken <678f76d0129c6a47299e3c6abb92ed26d253a960@canonical.com>

georghopp/lxd,benaryorg/lxd,lxc/lxd,lxc/lxd,hallyn/lxd,techtonik/lxd,achanda/lxd,stgraber/lxd,smoser/lxd,mjeanson/lxd,hallyn/lxd,lxc/lxd,hallyn/lxd,Malizor/lxd,jsavikko/lxd,hallyn/lxd,akshaykarle/lxd,Skarlso/lxd,lxc/lxd,stgraber/lxd,chrisglass/lxd,dustinkirkland/lxd,yura-pakhuchiy/lxd,smoser/lxd,yura-pakhuchiy/lxd,benaryorg/lxd,pcdummy/lxd,beni55/lxd,smoser/lxd,rrva/lxd,hallyn/lxd,ericsnowcurrently/lxd,chrisglass/lxd,mjeanson/lxd,jensg-st/lxd,rcj4747/lxd,atxwebs/lxd,erikmack/lxd,sl1pm4t/lxd,stgraber/lxd,pcdummy/lxd,stgraber/lxd,dustinkirkland/lxd,mikemccracken/lxd,lxc/lxd,atxwebs/lxd,achanda/lxd,sl1pm4t/lxd,yura-pakhuchiy/lxd,mikemccracken/lxd,sl1pm4t/lxd,erikmack/lxd,Skarlso/lxd,jumpstarter-io/lxd,atxwebs/lxd,dustinkirkland/lxd,rcj4747/lxd,beni55/lxd,ollie314/lxd,Skarlso/lxd,Skarlso/lxd,jsavikko/lxd,jsavikko/lxd,pcdummy/lxd,rrva/lxd,rrva/lxd,stgraber/lxd,atxwebs/lxd,beni55/lxd,techtonik/lxd,Malizor/lxd,chrisglass/lxd,achanda/lxd,akshaykarle/lxd,lxc/lxd,georghopp/lxd,stgraber/lxd,jensg-st/lxd,lxc/lxd,mikemccracken/lxd,Malizor/lxd,jumpstarter-io/lxd,ericsnowcurrently/lxd,ollie314/lxd,erikmack/lxd,jumpstarter-io/lxd,mjeanson/lxd,georghopp/lxd,techtonik/lxd,rcj4747/lxd,ericsnowcurrently/lxd,hallyn/lxd,benaryorg/lxd,stgraber/lxd,jensg-st/lxd,ollie314/lxd,akshaykarle/lxd