Travis updates (#50)

* Update to node 6.3.1

* Try adding mongodb as a devDependency

* Try the boron LTS?

* Try sudo:required

It worked in mongodb-js/data-service#68 so hopefully it works here too.

* Revert "Try adding mongodb as a devDependency"

This reverts commit a6606f3.

* Revert "Try the boron LTS?"

This reverts commit ced8aca.

* Try lts/boron

Let’s see if Travis correctly replaces it to 6.9.x

Author: pzrq

.travis.yml

@@ -1,6 +1,8 @@
 language: node_js
+sudo: required
 node_js:
-  - 5
+  - 6.3.1
+  - lts/boron
 script: npm run-script ci
 cache:
   directories: