Fixed incorrect comment on ACCESS_SANDBOX in authorizer.proto.
Fixed incorrect comment on ACCESS_SANDBOX in authorizer.proto.

The current semantic is that these fields might not be set.

Review: https://reviews.apache.org/r/49319/

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