add ability to get network info known by bitcoinjs-lib

Summary: `getNetwork` now takes an argument so the user can specify a network themselves. This is useful in bitgo-cli for the recoverlitecoin function, so we can specify the 'litecoin' network for initializing TransactionBuilder

Reviewers: arik, luis, benchan, barath

Reviewed By: barath

Subscribers: ben

Differential Revision: https://phabricator.bitgo.com/D5887

Author: Alex Melville

package.json

@@ -1,6 +1,6 @@
 {
   "name": "bitgo",
-  "version": "3.4.4",
+  "version": "3.4.5",
   "description": "BitGo Javascript SDK",
   "main": "./src/index.js",
   "keywords": [

src/bitcoin.js

@@ -21,8 +21,9 @@ if (isIE) {
   secp256k1 = undefined;
 }
 
-bitcoin.getNetwork = function() {
-  return bitcoin.networks[common.getNetwork()];
+bitcoin.getNetwork = function(network) {
+  network = network || common.getNetwork();
+  return bitcoin.networks[network];
 };
 
 bitcoin.makeRandomKey = function() {