Remove travis as we now have CircleCI.

.travis.yml

@@ -1,22 +0,0 @@
-language: node_js
-matrix:
-  include:
-    - os: osx
-      node_js: "6"
-    - os: osx
-      node_js: "8"
-    - os: osx
-      node_js: "9"
-install:
-  - npm install
-script:
-  - mkdir public
-  - node --stack_size=100000 $(which npm) run build
-  - npm run lint
-  - npm run lint-styles
-addons:
-  apt:
-    sources:
-      - ubuntu-toolchain-r-test
-    packages:
-      - g++-4.8