implement set-config

[nikr]

request:

# Default values here represent
# values at FV initialisation
# and not the default values 
# if parameters are omitted.
# -1 == no limit
{
 "flood-perm" : 
  {
   "slice-name" : <name>,
   "dpid" : <dpid> OPTIONAL
  },
    OPTIONAL DEFAULT NONE
 "flowmod-limit" :
  {
   "slice-name" : <name>,
   "dpid" : <dpid>,
   "limit" : <number>
  },
    OPTIONAL DEFAULT -1
  "track-flows" : <boolean>, 
    OPTIONAL DEFAULT false
 "stats-desc" : <boolean>, 
    OPTIONAL DEFAULT false
 "enable-topo-ctrl" : <boolean>,
    OPTIONAL DEFAULT false
 "flow-stats-cache" : <number>
    OPTIONAL DEFAULT 30 (seconds)
}

response: boolean