Update CI configs (#28)

Author: jwilsson

.travis.yml

@@ -1,11 +1,12 @@
 language: node_js
-node_js: "6"
+node_js: "8"
 
 os:
   - linux
   - osx
 
 sudo: false
+dist: trusty
 
 git:
   depth: 10

appveyor.yml

@@ -20,7 +20,7 @@ environment:
   - ATOM_CHANNEL: beta
 
 install:
-  - ps: Install-Product node 6
+  - ps: Install-Product node 8
 
 build_script:
   - ps: iex ((new-object net.webclient).DownloadString('https://raw.githubusercontent.com/atom/ci/master/build-package.ps1'))