Added queued and launched tasks to slave stats.
Added queued and launched tasks to slave stats.

Review: https://reviews.apache.org/r/17443

dforsyth/mesos,craimbert/mesos,dforsyth/mesos,Gilbert88/mesos,reneploetz/mesos,abudnik/mesos,zmalik/mesos,verizonlabs/mesos,Gilbert88/mesos,gsantovena/mesos,zmalik/mesos,yuquanshan/customizedMesos,yuquanshan/customizedMesos,kaysoky/mesos,reneploetz/mesos,asamerh4/mesos,gsantovena/mesos,Aman-Jain-14/customizedMesos,yuquanshan/customizedMesos,abudnik/mesos,craimbert/mesos,zmalik/mesos,Gilbert88/mesos,yuquanshan/customizedMesos,asamerh4/mesos,andschwa/mesos,jpeach/mesos,chhsia0/mesos,Aman-Jain-14/customizedMesos,dforsyth/mesos,Aman-Jain-14/customizedMesos,reneploetz/mesos,verizonlabs/mesos,gsantovena/mesos,chhsia0/mesos,reneploetz/mesos,kaysoky/mesos,kaysoky/mesos,gsantovena/mesos,yuquanshan/customizedMesos,craimbert/mesos,neilconway/mesos,abudnik/mesos,craimbert/mesos,zmalik/mesos,dforsyth/mesos,neilconway/mesos,dforsyth/mesos,Aman-Jain-14/customizedMesos,zmalik/mesos,asamerh4/mesos,gsantovena/mesos,Aman-Jain-14/customizedMesos,yuquanshan/customizedMesos,abudnik/mesos,asamerh4/mesos,dforsyth/mesos,craimbert/mesos,jpeach/mesos,chhsia0/mesos,Gilbert88/mesos,verizonlabs/mesos,andschwa/mesos,Aman-Jain-14/customizedMesos,reneploetz/mesos,reneploetz/mesos,gsantovena/mesos,verizonlabs/mesos,yuquanshan/customizedMesos,neilconway/mesos,andschwa/mesos,kaysoky/mesos,neilconway/mesos,kaysoky/mesos,verizonlabs/mesos,jpeach/mesos,Aman-Jain-14/customizedMesos,Gilbert88/mesos,abudnik/mesos,asamerh4/mesos,zmalik/mesos,abudnik/mesos,chhsia0/mesos,chhsia0/mesos,verizonlabs/mesos,jpeach/mesos,asamerh4/mesos,kaysoky/mesos,zmalik/mesos,chhsia0/mesos,andschwa/mesos,gsantovena/mesos,neilconway/mesos,neilconway/mesos,chhsia0/mesos,jpeach/mesos,Gilbert88/mesos,Gilbert88/mesos,jpeach/mesos,verizonlabs/mesos,dforsyth/mesos,andschwa/mesos,neilconway/mesos,jpeach/mesos,abudnik/mesos,kaysoky/mesos,asamerh4/mesos,andschwa/mesos,reneploetz/mesos,andschwa/mesos,craimbert/mesos,craimbert/mesos