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;

js/models/core/TxProposal.js

@@ -4,6 +4,7 @@ var bitcore = require('bitcore');
 var _ = require('underscore');
 var util = bitcore.util;
 var Transaction = bitcore.Transaction;
+var BuilderMockV0 = require('./BuilderMockV0');;
 var TransactionBuilder = bitcore.TransactionBuilder;
 var Script = bitcore.Script;
 var Key = bitcore.Key;
@@ -147,7 +148,12 @@ TxProposal.fromObj = function(o, forceOpts) {
   try {
     o.builder = TransactionBuilder.fromObj(o.builderObj);
   } catch (e) {
-    throw new Error("Invalid or Incompatible Backup Detected.");
+
+    // backwards (V0) compatatibility fix.
+    if (!o.version) {
+      o.builder = new BuilderMockV0(o.builderObj);
+      o.readonly = 1;
+    };
   }
   return new TxProposal(o);
 };

js/models/core/TxProposals.js

@@ -1,9 +1,11 @@
 'use strict';
 
+var BuilderMockV0 = require('./BuilderMockV0');;
 var bitcore = require('bitcore');
 var util = bitcore.util;
 var Transaction = bitcore.Transaction;
-var TxProposal = require('./TxProposal');
+var BuilderMockV0 = require('./BuilderMockV0');;
+var TxProposal = require('./TxProposal');;
 var Script = bitcore.Script;
 var Key = bitcore.Key;
 var buffertools = bitcore.buffertools;