update version to 0.1.9

The major changes in this version are:
* A new TransactionBuilder class to make it easy to make any kind of
 transaction.
* BIP32 - hierarchical deterministic wallets.
* Further progress towards full test coverage and 100% compatibility with
 bitcoin core.

package.json

@@ -1,7 +1,7 @@
 {
   "name": "bitcore",
   "description": "Bitcoin Library",
-  "version": "0.1.8",
+  "version": "0.1.9",
   "author": {
     "name": "Stephen Pair",
     "email": "stephen@bitpay.com"