Added support for authorization of Hierachical roles.
Added support for authorization of Hierachical roles.

Adds mechanisms to support authorization of hierarchical roles,
that is, it allows operators to write ACLs of the form role/%
which will enforce the rule for any nested role, e.g. role/a,
role/b and such.

Review: https://reviews.apache.org/r/57473/

Gilbert88/mesos,verizonlabs/mesos,andschwa/mesos,asamerh4/mesos,abudnik/mesos,jpeach/mesos,jpeach/mesos,neilconway/mesos,asamerh4/mesos,andschwa/mesos,asamerh4/mesos,neilconway/mesos,gsantovena/mesos,verizonlabs/mesos,andschwa/mesos,reneploetz/mesos,Gilbert88/mesos,andschwa/mesos,gsantovena/mesos,zmalik/mesos,abudnik/mesos,chhsia0/mesos,verizonlabs/mesos,neilconway/mesos,reneploetz/mesos,Gilbert88/mesos,asamerh4/mesos,gsantovena/mesos,verizonlabs/mesos,abudnik/mesos,asamerh4/mesos,zmalik/mesos,chhsia0/mesos,reneploetz/mesos,Gilbert88/mesos,kaysoky/mesos,kaysoky/mesos,gsantovena/mesos,dforsyth/mesos,verizonlabs/mesos,asamerh4/mesos,kaysoky/mesos,abudnik/mesos,reneploetz/mesos,reneploetz/mesos,jpeach/mesos,zmalik/mesos,chhsia0/mesos,Gilbert88/mesos,kaysoky/mesos,kaysoky/mesos,verizonlabs/mesos,neilconway/mesos,abudnik/mesos,zmalik/mesos,kaysoky/mesos,kaysoky/mesos,Gilbert88/mesos,asamerh4/mesos,jpeach/mesos,Gilbert88/mesos,dforsyth/mesos,jpeach/mesos,dforsyth/mesos,zmalik/mesos,neilconway/mesos,chhsia0/mesos,andschwa/mesos,gsantovena/mesos,dforsyth/mesos,gsantovena/mesos,dforsyth/mesos,neilconway/mesos,chhsia0/mesos,chhsia0/mesos,jpeach/mesos,neilconway/mesos,jpeach/mesos,reneploetz/mesos,andschwa/mesos,gsantovena/mesos,verizonlabs/mesos,zmalik/mesos,chhsia0/mesos,abudnik/mesos,dforsyth/mesos,abudnik/mesos,andschwa/mesos,reneploetz/mesos,dforsyth/mesos,zmalik/mesos