feat(build): Install vips on Travis.

Added vips to the Travis CI config.

Author: Alexandru Badiu

.travis.yml

@@ -7,7 +7,7 @@ notifications:
 node_js:
   - '8'
 before_install:
-  - npm install -g mocha
+  - apt-get install libvips
 after_success:
   - npm run semantic-release
 branches:

README.md

@@ -1,5 +1,5 @@
-[![Stories in Ready](https://badge.waffle.io/voidberg/imagecache.png?label=ready&title=Ready)](https://waffle.io/voidberg/imagecache-sharp)
-[![Latest release on NPM](https://img.shields.io/npm/v/imagecache.svg)](https://www.npmjs.com/package/imagecache-sharp)
+[![Stories in Ready](https://badge.waffle.io/voidberg/imagecache-sharp.png?label=ready&title=Ready)](https://waffle.io/voidberg/imagecache-sharp)
+[![Latest release on NPM](https://img.shields.io/npm/v/imagecache-sharp.svg)](https://www.npmjs.com/package/imagecache-sharp)
 [![Travis CI](https://travis-ci.org/voidberg/imagecache-sharp.svg?branch=master)](https://travis-ci.org/voidberg/imagecache-sharp)
 [![Commitizen friendly](https://img.shields.io/badge/commitizen-friendly-brightgreen.svg)](http://commitizen.github.io/cz-cli/)
 [![semantic-release](https://img.shields.io/badge/%20%20%F0%9F%93%A6%F0%9F%9A%80-semantic--release-e10079.svg)](https://github.com/semantic-release/semantic-release)