use _get_boolean() function instead of parsing api response in every method
use _get_boolean() function instead of parsing api response in every method

Closes #324

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

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