Remove Travis integration

The Travis integration is completely broken for 1.2.x due to some issue
with the npm cache and the linked packages created in it by the master
branch.  Remove it from here.

.travis.yml

@@ -1,10 +0,0 @@
-language: node_js
-node_js:
-  - 10
-before_install:
-  - sudo apt-get -qq update
-  - sudo apt-get install -y curl git tar
-  - curl -o factorio.tar.gz -L https://www.factorio.com/get-download/latest/headless/linux64
-  - tar -xvf factorio.tar.gz
-script:
-  - npm run cover