implement k-choices join functions

large commit, contains a number of things:
- k-choices #2 cost calculation
- k-choices parameters
- adjusting ASN.1 network messages to contain all values required for
  cost calculation #71
- adjusting stats to contain required values
- k-choices node and vserver join functions
- placeholder/ dummy invocation of k-choices join

FediChord.asn1

@@ -111,6 +111,7 @@ LoadRequestPayload ::= SEQUENCE {
 LoadResponsePayload ::= SEQUENCE {
 	loadSum					REAL,
 	remainingLoadTarget		REAL,
+	totalCapacity			REAL,
 	lowerBound				NodeID
 	}