Fix HDFS url description, and other various edits
Fix HDFS url description, and other various edits

HDFS url description is wrong as a result of code changes. This was
the major motivation for this CR.

Additional changes

* formatted for 80 characters
* consistent use of '.' at the end of bullets
* added mention of Spark
* adding '.sahara' suffix is no longer necessary
* some other minor changes

Closes-Bug: 1376457
Change-Id: I72134bcdf6c42911d07e65952a9a56331d896699

zhujzhuo/Sahara,openstack/sahara,matips/iosr-2015,zhujzhuo/Sahara,bigfootproject/sahara,zhujzhuo/Sahara,citrix-openstack-build/sahara,crobby/sahara,ekasitk/sahara,bigfootproject/sahara,tellesnobrega/sahara,citrix-openstack-build/sahara,crobby/sahara,esikachev/scenario,redhat-openstack/sahara,xme1226/sahara,crobby/sahara,openstack/sahara,xme1226/sahara,tellesnobrega/sahara,ekasitk/sahara,henaras/sahara,zhangjunli177/sahara,ekasitk/sahara,matips/iosr-2015,esikachev/sahara-backup,matips/iosr-2015,esikachev/sahara-backup,redhat-openstack/sahara,henaras/sahara,henaras/sahara,esikachev/scenario,esikachev/scenario,citrix-openstack-build/sahara,xme1226/sahara,zhangjunli177/sahara,redhat-openstack/sahara,egafford/sahara,bigfootproject/sahara,zhangjunli177/sahara,egafford/sahara,esikachev/sahara-backup