[LIBCLOUD-455] Don't throw if 'imageId' attribute is not present in the list_nodes response.
[LIBCLOUD-455] Don't throw if 'imageId' attribute is not present in the
list_nodes response.

Signed-off-by: Tomaz Muraus <bb4af54d4692022d34bcf290dffd91d21e083d18@apache.org>

techhat/libcloud,MrBasset/libcloud,pquentin/libcloud,mtekel/libcloud,marcinzaremba/libcloud,iPlantCollaborativeOpenSource/libcloud,mistio/libcloud,pantheon-systems/libcloud,munkiat/libcloud,DimensionDataCBUSydney/libcloud,watermelo/libcloud,NexusIS/libcloud,mbrukman/libcloud,wrigri/libcloud,ZuluPro/libcloud,sgammon/libcloud,aleGpereira/libcloud,mistio/libcloud,wrigri/libcloud,vongazman/libcloud,lochiiconnectivity/libcloud,erjohnso/libcloud,smaffulli/libcloud,iPlantCollaborativeOpenSource/libcloud,wuyuewen/libcloud,mathspace/libcloud,vongazman/libcloud,t-tran/libcloud,carletes/libcloud,sgammon/libcloud,samuelchong/libcloud,cloudControl/libcloud,DimensionDataCBUSydney/libcloud,MrBasset/libcloud,pquentin/libcloud,niteoweb/libcloud,jimbobhickville/libcloud,wido/libcloud,pquentin/libcloud,Verizon/libcloud,andrewsomething/libcloud,schaubl/libcloud,carletes/libcloud,supertom/libcloud,SecurityCompass/libcloud,erjohnso/libcloud,Kami/libcloud,dcorbacho/libcloud,iPlantCollaborativeOpenSource/libcloud,Itxaka/libcloud,schaubl/libcloud,aviweit/libcloud,JamesGuthrie/libcloud,pantheon-systems/libcloud,pantheon-systems/libcloud,cloudControl/libcloud,marcinzaremba/libcloud,Itxaka/libcloud,mistio/libcloud,NexusIS/libcloud,erjohnso/libcloud,curoverse/libcloud,curoverse/libcloud,illfelder/libcloud,ByteInternet/libcloud,mbrukman/libcloud,wuyuewen/libcloud,jerryblakley/libcloud,kater169/libcloud,Scalr/libcloud,illfelder/libcloud,dcorbacho/libcloud,thesquelched/libcloud,sfriesel/libcloud,sergiorua/libcloud,cryptickp/libcloud,aviweit/libcloud,ByteInternet/libcloud,cryptickp/libcloud,mgogoulos/libcloud,JamesGuthrie/libcloud,jimbobhickville/libcloud,lochiiconnectivity/libcloud,apache/libcloud,samuelchong/libcloud,sfriesel/libcloud,sahildua2305/libcloud,aleGpereira/libcloud,Kami/libcloud,kater169/libcloud,munkiat/libcloud,carletes/libcloud,sahildua2305/libcloud,briancurtin/libcloud,StackPointCloud/libcloud,sergiorua/libcloud,wrigri/libcloud,andrewsomething/libcloud,Cloud-Elasticity-Services/as-libcloud,t-tran/libcloud,marcinzaremba/libcloud,samuelchong/libcloud,SecurityCompass/libcloud,mathspace/libcloud,Scalr/libcloud,wido/libcloud,JamesGuthrie/libcloud,curoverse/libcloud,Cloud-Elasticity-Services/as-libcloud,StackPointCloud/libcloud,kater169/libcloud,thesquelched/libcloud,Kami/libcloud,Cloud-Elasticity-Services/as-libcloud,thesquelched/libcloud,mtekel/libcloud,smaffulli/libcloud,StackPointCloud/libcloud,aviweit/libcloud,lochiiconnectivity/libcloud,watermelo/libcloud,cloudControl/libcloud,dcorbacho/libcloud,techhat/libcloud,apache/libcloud,andrewsomething/libcloud,atsaki/libcloud,ClusterHQ/libcloud,briancurtin/libcloud,watermelo/libcloud,wuyuewen/libcloud,sergiorua/libcloud,atsaki/libcloud,ByteInternet/libcloud,ZuluPro/libcloud,vongazman/libcloud,briancurtin/libcloud,mbrukman/libcloud,smaffulli/libcloud,mtekel/libcloud,t-tran/libcloud,supertom/libcloud,SecurityCompass/libcloud,jimbobhickville/libcloud,NexusIS/libcloud,jerryblakley/libcloud,DimensionDataCBUSydney/libcloud,atsaki/libcloud,Scalr/libcloud,supertom/libcloud,wido/libcloud,illfelder/libcloud,MrBasset/libcloud,mgogoulos/libcloud,ZuluPro/libcloud,sahildua2305/libcloud,Itxaka/libcloud,Verizon/libcloud,apache/libcloud,aleGpereira/libcloud,schaubl/libcloud,mathspace/libcloud,niteoweb/libcloud,cryptickp/libcloud,ClusterHQ/libcloud,techhat/libcloud,jerryblakley/libcloud,mgogoulos/libcloud,sfriesel/libcloud,niteoweb/libcloud,Verizon/libcloud,munkiat/libcloud