Extended yarn ship: more automation

no issue

- added gulp task to extend casper release automation
- will draft the release for you
- will get the user facing commits from changelog
- runs after `yarn ship` (postship)
- full automation with env variables is possible

config.example.json

@@ -0,0 +1,6 @@
+{
+    "github": {
+        "username": "<username>",
+        "token": "<gh-personal-access-token>"
+    }
+}