providers/docker: don't pull if image is built
providers/docker: don't pull if image is built

crashlytics/vagrant,jkburges/vagrant,PatOShea/vagrant,darkn3rd/vagrant,sax/vagrant,h4ck3rm1k3/vagrant,lonniev/vagrant,mwarren/vagrant,PatOShea/vagrant,bheuvel/vagrant,tjanez/vagrant,dharmab/vagrant,wangfakang/vagrant,bshurts/vagrant,kalabiyau/vagrant,wangfakang/vagrant,vamegh/vagrant,marxarelli/vagrant,doy/vagrant,sni/vagrant,patrys/vagrant,mkuzmin/vagrant,loren-osborn/vagrant,tbarrongh/vagrant,genome21/vagrant,dustymabe/vagrant,patrys/vagrant,sni/vagrant,Endika/vagrant,jtopper/vagrant,jean/vagrant,bryson/vagrant,loren-osborn/vagrant,aaam/vagrant,taliesins/vagrant,dharmab/vagrant,mwarren/vagrant,Chhunlong/vagrant,stephancom/vagrant,muhanadra/vagrant,bdwyertech/vagrant,nickryand/vagrant,chrisroberts/vagrant,philoserf/vagrant,h4ck3rm1k3/vagrant,taliesins/vagrant,sni/vagrant,apertoso/vagrant,gpkfr/vagrant,fnewberg/vagrant,darkn3rd/vagrant,justincampbell/vagrant,johntron/vagrant,senglin/vagrant,krig/vagrant,chrisvire/vagrant,TheBigBear/vagrant,lonniev/vagrant,teotihuacanada/vagrant,myrjola/vagrant,aaam/vagrant,justincampbell/vagrant,denisbr/vagrant,benh57/vagrant,ArloL/vagrant,invernizzi-at-google/vagrant,petems/vagrant,darkn3rd/vagrant,Sgoettschkes/vagrant,sax/vagrant,dharmab/vagrant,blueyed/vagrant,benh57/vagrant,doy/vagrant,mitchellh/vagrant,janek-warchol/vagrant,jhoblitt/vagrant,jhoblitt/vagrant,dhoer/vagrant,modulexcite/vagrant,bheuvel/vagrant,petems/vagrant,apertoso/vagrant,bshurts/vagrant,loren-osborn/vagrant,dharmab/vagrant,carlosefr/vagrant,philoserf/vagrant,philoserf/vagrant,Chhed13/vagrant,nickryand/vagrant,jberends/vagrant,zsjohny/vagrant,pwnall/vagrant,sax/vagrant,carlosefr/vagrant,doy/vagrant,TheBigBear/vagrant,crashlytics/vagrant,modulexcite/vagrant,tomfanning/vagrant,mpoeter/vagrant,loren-osborn/vagrant,bshurts/vagrant,dhoer/vagrant,philoserf/vagrant,tschortsch/vagrant,invernizzi-at-google/vagrant,janek-warchol/vagrant,tjanez/vagrant,Sgoettschkes/vagrant,doy/vagrant,vamegh/vagrant,stephancom/vagrant,kamazee/vagrant,gpkfr/vagrant,sax/vagrant,gpkfr/vagrant,dustymabe/vagrant,jkburges/vagrant,vamegh/vagrant,tbarrongh/vagrant,Avira/vagrant,Chhed13/vagrant,jberends/vagrant,carlosefr/vagrant,marxarelli/vagrant,kamigerami/vagrant,pwnall/vagrant,genome21/vagrant,aneeshusa/vagrant,jtopper/vagrant,jberends/vagrant,sni/vagrant,jmanero/vagrant,apertoso/vagrant,zsjohny/vagrant,PatrickLang/vagrant,teotihuacanada/vagrant,mitchellh/vagrant,myrjola/vagrant,denisbr/vagrant,gitebra/vagrant,senglin/vagrant,mpoeter/vagrant,Avira/vagrant,fnewberg/vagrant,tomfanning/vagrant,TheBigBear/vagrant,kalabiyau/vagrant,mwrock/vagrant,kamigerami/vagrant,chrisroberts/vagrant,signed8bit/vagrant,justincampbell/vagrant,gbarberi/vagrant,dhoer/vagrant,mwrock/vagrant,ianmiell/vagrant,benizi/vagrant,benizi/vagrant,tschortsch/vagrant,tjanez/vagrant,mitchellh/vagrant,patrys/vagrant,tomfanning/vagrant,Chhed13/vagrant,myrjola/vagrant,signed8bit/vagrant,aaam/vagrant,PatrickLang/vagrant,PatrickLang/vagrant,krig/vagrant,bheuvel/vagrant,lonniev/vagrant,bdwyertech/vagrant,bryson/vagrant,Chhunlong/vagrant,ArloL/vagrant,zsjohny/vagrant,mitchellh/vagrant,benh57/vagrant,aneeshusa/vagrant,mpoeter/vagrant,invernizzi-at-google/vagrant,stephancom/vagrant,janek-warchol/vagrant,benh57/vagrant,jfchevrette/vagrant,ianmiell/vagrant,mwrock/vagrant,jhoblitt/vagrant,kalabiyau/vagrant,marxarelli/vagrant,benizi/vagrant,denisbr/vagrant,TheBigBear/vagrant,ianmiell/vagrant,PatrickLang/vagrant,mkuzmin/vagrant,jkburges/vagrant,Endika/vagrant,jkburges/vagrant,cgvarela/vagrant,tbarrongh/vagrant,h4ck3rm1k3/vagrant,tbriggs-curse/vagrant,tbarrongh/vagrant,mwarren/vagrant,cgvarela/vagrant,chrisvire/vagrant,kamazee/vagrant,pwnall/vagrant,ArloL/vagrant,kalabiyau/vagrant,PatOShea/vagrant,dhoer/vagrant,benizi/vagrant,tschortsch/vagrant,tjanez/vagrant,signed8bit/vagrant,jfchevrette/vagrant,bshurts/vagrant,chrisvire/vagrant,dustymabe/vagrant,lukebakken/vagrant,johntron/vagrant,Chhunlong/vagrant,Chhunlong/vagrant,chrisroberts/vagrant,gbarberi/vagrant,bdwyertech/vagrant,zsjohny/vagrant,lukebakken/vagrant,jtopper/vagrant,lonniev/vagrant,bdwyertech/vagrant,modulexcite/vagrant,denisbr/vagrant,mkuzmin/vagrant,kamazee/vagrant,bryson/vagrant,signed8bit/vagrant,jtopper/vagrant,kamigerami/vagrant,carlosefr/vagrant,Chhed13/vagrant,tomfanning/vagrant,cgvarela/vagrant,crashlytics/vagrant,gitebra/vagrant,teotihuacanada/vagrant,senglin/vagrant,taliesins/vagrant,jean/vagrant,kamazee/vagrant,jmanero/vagrant,cgvarela/vagrant,wangfakang/vagrant,gitebra/vagrant,muhanadra/vagrant,genome21/vagrant,crashlytics/vagrant,nickryand/vagrant,Sgoettschkes/vagrant,senglin/vagrant,Endika/vagrant,petems/vagrant,h4ck3rm1k3/vagrant,ArloL/vagrant,bryson/vagrant,krig/vagrant,ianmiell/vagrant,taliesins/vagrant,nickryand/vagrant,mwrock/vagrant,jean/vagrant,jmanero/vagrant,modulexcite/vagrant,aneeshusa/vagrant,vamegh/vagrant,Avira/vagrant,jberends/vagrant,tbriggs-curse/vagrant,tschortsch/vagrant,mpoeter/vagrant,jfchevrette/vagrant,blueyed/vagrant,Avira/vagrant,PatOShea/vagrant,jean/vagrant,johntron/vagrant,invernizzi-at-google/vagrant,tbriggs-curse/vagrant,teotihuacanada/vagrant,Endika/vagrant,blueyed/vagrant,apertoso/vagrant,muhanadra/vagrant,dustymabe/vagrant,kamigerami/vagrant,blueyed/vagrant,lukebakken/vagrant,lukebakken/vagrant,gpkfr/vagrant,wangfakang/vagrant,fnewberg/vagrant,gbarberi/vagrant,jfchevrette/vagrant,marxarelli/vagrant,pwnall/vagrant,chrisroberts/vagrant,fnewberg/vagrant,Sgoettschkes/vagrant,gitebra/vagrant,tbriggs-curse/vagrant,genome21/vagrant,petems/vagrant,johntron/vagrant,jmanero/vagrant,darkn3rd/vagrant,aneeshusa/vagrant,patrys/vagrant,janek-warchol/vagrant,stephancom/vagrant,aaam/vagrant,muhanadra/vagrant,myrjola/vagrant,chrisvire/vagrant,bheuvel/vagrant,mwarren/vagrant,justincampbell/vagrant,jhoblitt/vagrant,mkuzmin/vagrant,gbarberi/vagrant,krig/vagrant