Amend install instructions to cover dependency missing from mesos deb.
Amend install instructions to cover dependency missing from mesos deb.

Reviewed at https://reviews.apache.org/r/42017/

rdelval/aurora,apache/aurora,thinker0/aurora,apache/aurora,crashlytics/aurora,rdelval/aurora,protochron/aurora,crashlytics/aurora,apache/aurora,protochron/aurora,rdelval/aurora,crashlytics/aurora,medallia/aurora,thinker0/aurora,thinker0/aurora,thinker0/aurora,medallia/aurora,protochron/aurora,apache/aurora,crashlytics/aurora,apache/aurora,protochron/aurora,protochron/aurora,crashlytics/aurora,rdelval/aurora,rdelval/aurora,rdelval/aurora,medallia/aurora,medallia/aurora,thinker0/aurora,medallia/aurora,medallia/aurora,apache/aurora,protochron/aurora,thinker0/aurora,crashlytics/aurora