Got etherscan working, bump version

New version of provider-engine includes etherscan-subprovider features required to let Metamask use it.

Hard coded the new version of `web3-provider-engine` even though it is not live on `npm` yet, because it is a dependency of this branch.

I'll deploy to the Chrome store but not merge on Github until that provider-engine is published, because it could break others' dev environments.

app/manifest.json

@@ -1,7 +1,7 @@
 {
   "name": "__MSG_appName__",
   "short_name": "Metamask",
-  "version": "1.2.1",
+  "version": "1.3.0",
   "manifest_version": 2,
   "description": "__MSG_appDescription__",
   "icons": {

package.json

@@ -27,7 +27,7 @@
     "readable-stream": "^2.0.5",
     "through2": "^2.0.1",
     "web3": "^0.15.1",
-    "web3-provider-engine": "^7.0.0",
+    "web3-provider-engine": "^7.2.1",
     "xtend": "^4.0.1"
   },
   "devDependencies": {