Bump version to MINOR release 2.7.0

Features:
* Add support for Developer Preview features under a new preview tag
* Add roomHint property to smart home response
* Adds types for 2FA in smart home request/responses

Fixes:
* Fix conv.data not set when init.data has changed issue
* Fix package.json to correct Node version >=6.13.0
* Add warning for using DeepLink

Other Changes:
* Update dependencies for security
* Change library development tooling

Change-Id: I370808e3a52564304cfc2cdd94c1866beb198ca1

package.json

@@ -3,7 +3,7 @@
   "description": "Actions on Google Client Library for Node.js",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
-  "version": "2.6.0",
+  "version": "2.7.0",
   "license": "Apache-2.0",
   "author": "Google Inc.",
   "engines": {