Revert "Delete BuilderMockV0"

This is a combination of 3 commits:
* Revertion of commit b39a683339.
* Revertion of commit 61aea8db3d.
* Revertion of commit 5f666aef66.

js/models/core/BuilderMockV0.js

@@ -0,0 +1,26 @@
+'use strict';
+
+
+var bitcore = require('bitcore');
+var Transaction = bitcore.Transaction;
+
+function BuilderMockV0 (data) {
+  this.vanilla = data;
+  this.tx = new Transaction();
+  this.tx.parse(new Buffer(data.tx, 'hex'));
+};
+
+BuilderMockV0.prototype.build = function() {
+  return this.tx;
+}; 
+
+
+BuilderMockV0.prototype.getSelectedUnspent = function() {
+  return [];
+};
+
+BuilderMockV0.prototype.toObj = function() {
+  return this.vanilla;
+};
+
+module.exports = BuilderMockV0;