Added DiskInfo to the Resource protobuf.
Added DiskInfo to the Resource protobuf.

Review: https://reviews.apache.org/r/27550

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