Properly capitalize BufferUtil everywhere

Right out of CONTRIBUTING.md

https://github.com/bitpay/bitcore/blob/master/CONTRIBUTING.md#g6---naming-utility-namespaces

lib/crypto/point.js

@@ -1,7 +1,7 @@
 'use strict';
 
 var BN = require('./bn');
-var bufferUtil = require('../util/buffer');
+var BufferUtil = require('../util/buffer');
 var ec = require('elliptic').curves.secp256k1;
 var ecPoint = ec.curve.point.bind(ec.curve);
 var ecPointFromX = ec.curve.pointFromX.bind(ec.curve);
@@ -139,7 +139,7 @@ Point.pointToCompressed = function pointToCompressed(point) {
   } else {
     prefix = new Buffer([0x02]);
   }
-  return bufferUtil.concat([prefix, xbuf]);
+  return BufferUtil.concat([prefix, xbuf]);
 };
 
 module.exports = Point;

lib/encoding/bufferreader.js

@@ -2,7 +2,7 @@
 
 var _ = require('lodash');
 var $ = require('../util/preconditions');
-var bufferUtil = require('../util/buffer');
+var BufferUtil = require('../util/buffer');
 var BN = require('../crypto/bn');
 
 var BufferReader = function BufferReader(buf) {
@@ -166,7 +166,7 @@ BufferReader.prototype.readReverse = function(len) {
   }
   var buf = this.buf.slice(this.pos, this.pos + len);
   this.pos = this.pos + len;
-  return bufferUtil.reverse(buf);
+  return BufferUtil.reverse(buf);
 };
 
 module.exports = BufferReader;

lib/transaction/transaction.js

@@ -5,7 +5,7 @@ var $ = require('../util/preconditions');
 var buffer = require('buffer');
 
 var errors = require('../errors');
-var bufferUtil = require('../util/buffer');
+var BufferUtil = require('../util/buffer');
 var JSUtil = require('../util/js');
 var BufferReader = require('../encoding/bufferreader');
 var BufferWriter = require('../encoding/bufferwriter');
@@ -50,7 +50,7 @@ function Transaction(serialized) {
       this.fromString(serialized);
     } else if (JSUtil.isValidJSON(serialized)) {
       this.fromJSON(serialized);
-    } else if (bufferUtil.isBuffer(serialized)) {
+    } else if (BufferUtil.isBuffer(serialized)) {
       this.fromBuffer(serialized);
     } else if (_.isObject(serialized)) {
       this.fromObject(serialized);

test/hdpublickey.js

@@ -9,7 +9,7 @@ var bitcore = require('..');
 var buffer = require('buffer');
 var errors = bitcore.errors;
 var hdErrors = bitcore.errors.HDPublicKey;
-var bufferUtil = bitcore.util.buffer;
+var BufferUtil = bitcore.util.buffer;
 var HDPrivateKey = bitcore.HDPrivateKey;
 var HDPublicKey = bitcore.HDPublicKey;
 var Base58Check = bitcore.encoding.Base58Check;
@@ -117,7 +117,7 @@ describe('HDPublicKey interface', function() {
 
     it('checks the checksum', function() {
       var buffers = new HDPublicKey(xpubkey)._buffers;
-      buffers.checksum = bufferUtil.integerAsBuffer(1);
+      buffers.checksum = BufferUtil.integerAsBuffer(1);
       expectFail(function() {
         return new HDPublicKey(buffers);
       }, errors.InvalidB58Checksum);