[CHORE] Update .travis.yml

Remove some deprecated config settings for Travis.
Update settings to more closely align with the default addon output,
see https://github.com/ember-cli/ember-addon-output/blob/master/.travis.yml

.travis.yml

@@ -5,44 +5,58 @@ node_js:
   # so that your addon works for all apps
   - '8'
 
-sudo: required
 dist: trusty
 
 addons:
   chrome: stable
 
 cache:
   yarn: true
+  directories:
+    - node_modules
 
-global:
-  # See https://git.io/vdao3 for details.
-  - JOBS=1
 env:
-  # we recommend new addons test the current and previous LTS
-  # as well as latest stable release (bonus points to beta/canary)
-  - EMBER_TRY_SCENARIO=ember-1.12
-  - EMBER_TRY_SCENARIO=ember-1.13
-  - EMBER_TRY_SCENARIO=ember-lts-2.8
-  - EMBER_TRY_SCENARIO=ember-lts-2.18
-  - EMBER_TRY_SCENARIO=ember-release
-  - EMBER_TRY_SCENARIO=ember-beta
-  - EMBER_TRY_SCENARIO=ember-canary
-  - EMBER_TRY_SCENARIO=ember-default
-
-matrix:
-  fast_finish: true
+  global:
+    # See https://git.io/vdao3 for details.
+    - JOBS=1
+
+branches:
+  only:
+    - master
+    # npm version tags
+    - /^v\d+\.\d+\.\d+/
+
+jobs:
+  fail_fast: true
   allow_failures:
     - env: EMBER_TRY_SCENARIO=ember-canary
 
-before_install:
-  - curl -o- -L https://yarnpkg.com/install.sh | bash
-  - export PATH=$HOME/.yarn/bin:$PATH
+  include:
+    # runs linting and tests with current locked deps
+
+    - stage: 'Tests'
+      name: 'Tests'
+      script:
+        - yarn run lint
+        - yarn run test
+
+    # we recommend new addons test the current and previous LTS
+    # as well as latest stable release (bonus points to beta/canary)
+    - stage: 'Additional Tests'
+      env: EMBER_TRY_SCENARIO=ember-1.12
+    - env: EMBER_TRY_SCENARIO=ember-1.13
+    - env: EMBER_TRY_SCENARIO=ember-lts-2.8
+    - env: EMBER_TRY_SCENARIO=ember-lts-2.18
+    - env: EMBER_TRY_SCENARIO=ember-lts-3.4
+    - env: EMBER_TRY_SCENARIO=ember-lts-3.8
+    - env: EMBER_TRY_SCENARIO=ember-release
+    - env: EMBER_TRY_SCENARIO=ember-beta
+    - env: EMBER_TRY_SCENARIO=ember-canary
 
 install:
   - yarn install --no-lockfile --non-interactive
 
 script:
-  - yarn run lint
   # Usually, it's ok to finish the test scenario without reverting
   #  to the addon's original dependency state, skipping "cleanup".
   - node_modules/.bin/ember try:one $EMBER_TRY_SCENARIO --skip-cleanup