Optimization of ceilometer API
Optimization of ceilometer API

- optimizing requests for resource by multithreading on resource level
  (each resource is obtaining stats in separate thread)
- fix last comment addressed in review
  https://review.openstack.org/#/c/35589/
- fixing typos and misleading comments

Fixes bug 1218407
Change-Id: I24826bac7679bd075792691e3ed9a342aa1659fb

citrix-openstack-build/horizon,maestro-hybrid-cloud/horizon,orbitfp7/horizon,BiznetGIO/horizon,maestro-hybrid-cloud/horizon,nvoron23/avos,froyobin/horizon,flochaz/horizon,saydulk/horizon,xinwu/horizon,tellesnobrega/horizon,django-leonardo/horizon,newrocknj/horizon,j4/horizon,damien-dg/horizon,Mirantis/mos-horizon,henaras/horizon,FNST-OpenStack/horizon,icloudrnd/automation_tools,philoniare/horizon,BiznetGIO/horizon,j4/horizon,Solinea/horizon,yanheven/console,sandvine/horizon,ChameleonCloud/horizon,takeshineshiro/horizon,CiscoSystems/horizon,Solinea/horizon,gochist/horizon,yjxtogo/horizon,yanheven/console,blueboxgroup/horizon,Metaswitch/horizon,liyitest/rr,doug-fish/horizon,agileblaze/OpenStackTwoFactorAuthentication,coreycb/horizon,bac/horizon,orbitfp7/horizon,endorphinl/horizon,liyitest/rr,davidcusatis/horizon,vladryk/horizon,Mirantis/mos-horizon,mrunge/openstack_horizon,noironetworks/horizon,Hodorable/0602,philoniare/horizon,BiznetGIO/horizon,froyobin/horizon,yeming233/horizon,doug-fish/horizon,Metaswitch/horizon,wangxiangyu/horizon,promptworks/horizon,Daniex/horizon,tsufiev/horizon,bigswitch/horizon,NCI-Cloud/horizon,CiscoSystems/avos,Hodorable/0602,FNST-OpenStack/horizon,coreycb/horizon,django-leonardo/horizon,saydulk/horizon,dan1/horizon-proto,maestro-hybrid-cloud/horizon,mandeepdhami/horizon,karthik-suresh/horizon,Tesora/tesora-horizon,kaiweifan/horizon,luhanhan/horizon,wangxiangyu/horizon,Dark-Hacker/horizon,bigswitch/horizon,Solinea/horizon,tellesnobrega/horizon,liyitest/rr,CiscoSystems/avos,openstack/horizon,ikargis/horizon_fod,zouyapeng/horizon,Daniex/horizon,rickerc/horizon_audit,anthonydillon/horizon,Mirantis/mos-horizon,eayunstack/horizon,yeming233/horizon,RudoCris/horizon,NCI-Cloud/horizon,blueboxgroup/horizon,aaronorosen/horizon-congress,rickerc/horizon_audit,sandvine/horizon,NCI-Cloud/horizon,Dark-Hacker/horizon,karthik-suresh/horizon,dan1/horizon-x509,takeshineshiro/horizon,coreycb/horizon,agileblaze/OpenStackTwoFactorAuthentication,karthik-suresh/horizon,aaronorosen/horizon-congress,karthik-suresh/horizon,idjaw/horizon,saydulk/horizon,dan1/horizon-x509,NeCTAR-RC/horizon,coreycb/horizon,xinwu/horizon,icloudrnd/automation_tools,VaneCloud/horizon,ging/horizon,gerrive/horizon,wolverineav/horizon,idjaw/horizon,takeshineshiro/horizon,promptworks/horizon,endorphinl/horizon-fork,anthonydillon/horizon,bigswitch/horizon,redhat-cip/horizon,endorphinl/horizon-fork,JioCloud/horizon,redhat-openstack/horizon,yanheven/console,xinwu/horizon,dan1/horizon-x509,tellesnobrega/horizon,newrocknj/horizon,tanglei528/horizon,mandeepdhami/horizon,VaneCloud/horizon,izadorozhna/dashboard_integration_tests,flochaz/horizon,Hodorable/0602,pranavtendolkr/horizon,liyitest/rr,tqtran7/horizon,ging/horizon,Tesora/tesora-horizon,tsufiev/horizon,redhat-openstack/horizon,zouyapeng/horizon,endorphinl/horizon,luhanhan/horizon,endorphinl/horizon,kaiweifan/horizon,mandeepdhami/horizon,pranavtendolkr/horizon,gochist/horizon,aaronorosen/horizon-congress,watonyweng/horizon,anthonydillon/horizon,davidcusatis/horizon,gerrive/horizon,blueboxgroup/horizon,philoniare/horizon,bac/horizon,redhat-openstack/horizon,Daniex/horizon,froyobin/horizon,idjaw/horizon,citrix-openstack-build/horizon,doug-fish/horizon,Tesora/tesora-horizon,gerrive/horizon,vladryk/horizon,CiscoSystems/avos,sandvine/horizon,spring-week-topos/horizon-week,citrix-openstack-build/horizon,endorphinl/horizon-fork,kfox1111/horizon,pranavtendolkr/horizon,j4/horizon,newrocknj/horizon,ging/horizon,vladryk/horizon,philoniare/horizon,redhat-cip/horizon,doug-fish/horizon,mrunge/horizon,yjxtogo/horizon,spring-week-topos/horizon-week,CiscoSystems/avos,VaneCloud/horizon,CiscoSystems/horizon,mrunge/horizon_lib,tqtran7/horizon,openstack/horizon,tsufiev/horizon,mandeepdhami/horizon,luhanhan/horizon,sandvine/horizon,spring-week-topos/horizon-week,Dark-Hacker/horizon,watonyweng/horizon,dan1/horizon-proto,tqtran7/horizon,tsufiev/horizon,takeshineshiro/horizon,mrunge/horizon_lib,kfox1111/horizon,Tesora/tesora-horizon,davidcusatis/horizon,orbitfp7/horizon,mdavid/horizon,redhat-cip/horizon,noironetworks/horizon,RudoCris/horizon,Dark-Hacker/horizon,j4/horizon,izadorozhna/dashboard_integration_tests,mrunge/openstack_horizon,damien-dg/horizon,flochaz/horizon,Hodorable/0602,mdavid/horizon,tqtran7/horizon,Metaswitch/horizon,watonyweng/horizon,henaras/horizon,mrunge/horizon,django-leonardo/horizon,icloudrnd/automation_tools,idjaw/horizon,promptworks/horizon,kfox1111/horizon,bigswitch/horizon,Metaswitch/horizon,FNST-OpenStack/horizon,icloudrnd/automation_tools,xme1226/horizon,JioCloud/horizon,vladryk/horizon,noironetworks/horizon,tanglei528/horizon,ChameleonCloud/horizon,gerrive/horizon,kaiweifan/horizon,yjxtogo/horizon,mrunge/horizon,NeCTAR-RC/horizon,wolverineav/horizon,nvoron23/avos,ikargis/horizon_fod,anthonydillon/horizon,yeming233/horizon,NCI-Cloud/horizon,endorphinl/horizon-fork,RudoCris/horizon,blueboxgroup/horizon,mdavid/horizon,Daniex/horizon,rickerc/horizon_audit,dan1/horizon-x509,tellesnobrega/horizon,endorphinl/horizon,bac/horizon,openstack/horizon,flochaz/horizon,mrunge/horizon_lib,zouyapeng/horizon,promptworks/horizon,eayunstack/horizon,redhat-cip/horizon,newrocknj/horizon,NeCTAR-RC/horizon,VaneCloud/horizon,ikargis/horizon_fod,damien-dg/horizon,yjxtogo/horizon,mdavid/horizon,wolverineav/horizon,django-leonardo/horizon,damien-dg/horizon,CiscoSystems/horizon,eayunstack/horizon,yeming233/horizon,luhanhan/horizon,nvoron23/avos,saydulk/horizon,davidcusatis/horizon,orbitfp7/horizon,FNST-OpenStack/horizon,dan1/horizon-proto,noironetworks/horizon,henaras/horizon,dan1/horizon-proto,ging/horizon,xme1226/horizon,JioCloud/horizon,Mirantis/mos-horizon,NeCTAR-RC/horizon,pranavtendolkr/horizon,openstack/horizon,watonyweng/horizon,zouyapeng/horizon,wolverineav/horizon,nvoron23/avos,ChameleonCloud/horizon,BiznetGIO/horizon,ChameleonCloud/horizon,redhat-openstack/horizon,agileblaze/OpenStackTwoFactorAuthentication,kfox1111/horizon,CiscoSystems/horizon,tanglei528/horizon,agileblaze/OpenStackTwoFactorAuthentication,xme1226/horizon,mrunge/openstack_horizon,RudoCris/horizon,Solinea/horizon,gochist/horizon,bac/horizon,maestro-hybrid-cloud/horizon,xinwu/horizon,henaras/horizon,wangxiangyu/horizon,wangxiangyu/horizon