Added retry around apt-get
Added retry around apt-get

Added a retry mechanism around apt-get to avoid failures
caused by something else running apt-get.
apt-get is called until success or error different from
the one caused by dpkg lock

bz2/juju,bogdanteleaga/juju,marcmolla/juju,mikemccracken/juju,Altoros/juju-cloudsigma,fwereade/juju,kat-co/juju,bac/juju,wwitzel3/juju,mhilton/juju,howbazaar/juju,Altoros/juju-cloudsigma,cloud-green/juju,dimitern/juju,ericsnowcurrently/juju,tych0/juju,tsakas/juju,voidspace/juju,bac/juju,marcmolla/juju,thomnico/juju,tsakas/juju,alesstimec/juju,axw/juju,mjs/juju,mikemccracken/juju,sinzui/juju,tych0/juju,howbazaar/juju,mjs/juju,voidspace/juju,kat-co/juju,jrwren/juju,perrito666/juju,reedobrien/juju,cloud-green/juju,tych0/juju,bogdanteleaga/juju,perrito666/juju,sinzui/juju,dooferlad/juju,mhilton/juju-juju,howbazaar/juju,reedobrien/juju,davecheney/juju,davecheney/juju,cloud-green/juju,axw/juju,mhilton/juju,mjs/juju,jrwren/juju,alesstimec/juju,tasdomas/juju,mhilton/juju-juju,alesstimec/juju,makyo/juju,Altoros/juju-vmware,davecheney/juju,cherylj/juju,bz2/juju,thomnico/juju,bac/juju,macgreagoir/juju,thomnico/juju,marcmolla/juju,frankban/juju-tmp,gabriel-samfira/juju,bz2/juju,Altoros/juju-vmware,AdamIsrael/juju,alesstimec/juju,tasdomas/juju,frankban/juju-tmp,makyo/juju,gabriel-samfira/juju,AdamIsrael/juju,ericsnowcurrently/juju,cmars/juju,fwereade/juju,cherylj/juju,axw/juju,macgreagoir/juju,makyo/juju,sinzui/juju,dooferlad/juju,tsakas/juju,kat-co/juju,waigani/juju,fwereade/juju,perrito666/juju,dimitern/juju,frankban/juju-tmp,anastasiamac/juju,wwitzel3/juju,ericsnowcurrently/juju,mjs/juju,anastasiamac/juju,macgreagoir/juju,cherylj/juju,gabriel-samfira/juju,cloud-green/juju,mhilton/juju,frankban/juju-tmp,mhilton/juju-juju,ericsnowcurrently/juju,marcmolla/juju,bz2/juju,cmars/juju,macgreagoir/juju,jrwren/juju,Altoros/juju-cloudsigma,Altoros/juju-vmware,waigani/juju,frankban/juju,bac/juju,mikemccracken/juju,bogdanteleaga/juju,reedobrien/juju,axw/juju,howbazaar/juju,marcoceppi/juju,alesstimec/juju,ericsnowcurrently/juju,AdamIsrael/juju,anastasiamac/juju,thomnico/juju,wwitzel3/juju,marcoceppi/juju,frankban/juju,dooferlad/juju,cmars/juju,frankban/juju,mjs/juju,frankban/juju,mjs/juju,perrito666/juju,bac/juju,reedobrien/juju,davecheney/juju,wwitzel3/juju,perrito666/juju,dooferlad/juju,frankban/juju,waigani/juju,tych0/juju,mhilton/juju,tasdomas/juju,cmars/juju,dimitern/juju,mhilton/juju-juju,bogdanteleaga/juju,mjs/juju,anastasiamac/juju,kat-co/juju,makyo/juju,axw/juju,AdamIsrael/juju,voidspace/juju,dimitern/juju,bz2/juju,gabriel-samfira/juju,waigani/juju,anastasiamac/juju,Altoros/juju-cloudsigma,marcoceppi/juju,reedobrien/juju,marcoceppi/juju,dimitern/juju,kat-co/juju,voidspace/juju,Altoros/juju-vmware,mikemccracken/juju,tasdomas/juju,dooferlad/juju,fwereade/juju,marcmolla/juju,sinzui/juju,mikemccracken/juju,cherylj/juju,howbazaar/juju,macgreagoir/juju,gabriel-samfira/juju,tsakas/juju