Log entry max to 2k, remove logging in hot codepaths (#1459)

On a recent trip through a CPU profile taken while Signal Desktop
churned through a large backlog of messages, it was clear that
console.log was a major source of time spent, primarily the sort
operation required after every new entry is added to the Backbone
collection. So, three different techniques to combat this:

1) Reduce the maximum number of entries in the collection from 5k to 2k
2) No more logging of add/update/remove queue in MessageReceiver
3) No more log entries in Message.handleDataMessage main codepath

FREEBIE

libtextsecure/message_receiver.js

@@ -236,7 +236,6 @@ MessageReceiver.prototype.extend({
     },
     addToCache: function(envelope, plaintext) {
         var id = this.getEnvelopeId(envelope);
-        console.log('addToCache', id);
         var data = {
             id: id,
             envelope: plaintext,
@@ -247,7 +246,6 @@ MessageReceiver.prototype.extend({
     },
     updateCache: function(envelope, plaintext) {
         var id = this.getEnvelopeId(envelope);
-        console.log('updateCache', id);
         var data = {
             decrypted: plaintext
         };
@@ -255,7 +253,6 @@ MessageReceiver.prototype.extend({
     },
     removeFromCache: function(envelope) {
         var id = this.getEnvelopeId(envelope);
-        console.log('removeFromCache', id);
         return textsecure.storage.unprocessed.remove(id);
     },
     queueDecryptedEnvelope: function(envelope, plaintext) {