Minor reorganization of broctl README to avoid redundancy

Reorganized a few sections of the document to avoid having the same
information in multiple locations.  Made the use of prefix more consistent
in the examples.  Corrected several typos.
Add broctl option to set PF_RING cluster type

Added a new broctl option "PFRINGClusterType", which allows a user
to specify a PF_RING cluster type (the default is the same cluster
type used in previous versions of broctl).  The broctl pf_ring plugin
will use this information to set the correct environment variable
which is needed by the PF_RING-aware libpcap to set the cluster type.

Addresses BIT-1108
Merge remote-tracking branch 'origin/master' into topic/dnthayer/doc-updates
Merge remote-tracking branch 'origin/topic/dnthayer/doc-updates'

* origin/topic/dnthayer/doc-updates:
  Minor reorganization of broctl README to avoid redundancy
Change default PF_RING cluster type to 4-tuple
Add tests of the new PFRINGClusterType broctl option
Merge remote-tracking branch 'origin/topic/dnthayer/ticket1108'

* origin/topic/dnthayer/ticket1108:
  Add tests of the new PFRINGClusterType broctl option
  Change default PF_RING cluster type to 4-tuple
  Add broctl option to set PF_RING cluster type

BIT-1108 #merged
Merge remote-tracking branch 'origin/master' into topic/dnthayer/misc-improvements