fix(ci): use Travis for Windows builds

This commit fixes failing CI and updates the list of checked Node versions to included the latest LTS releases. The main change is that it drops AppVeyor in favor of Travis for Windows builds.

.travis.yml

@@ -1,6 +1,15 @@
 sudo: false
+
 language: node_js
+
 node_js:
-  - '0.12'
-  - '4'
-  - '5'
+- '0.12'
+- '4'
+- '6'
+- '8'
+- '10'
+
+os:
+- windows
+- linux
+- osx

README.md

@@ -3,7 +3,6 @@
 [![Build Status](https://travis-ci.org/tapjs/signal-exit.png)](https://travis-ci.org/tapjs/signal-exit)
 [![Coverage](https://coveralls.io/repos/tapjs/signal-exit/badge.svg?branch=master)](https://coveralls.io/r/tapjs/signal-exit?branch=master)
 [![NPM version](https://img.shields.io/npm/v/signal-exit.svg)](https://www.npmjs.com/package/signal-exit)
-[![Windows Tests](https://img.shields.io/appveyor/ci/bcoe/signal-exit/master.svg?label=Windows%20Tests)](https://ci.appveyor.com/project/bcoe/signal-exit)
 [![Standard Version](https://img.shields.io/badge/release-standard%20version-brightgreen.svg)](https://github.com/conventional-changelog/standard-version)
 
 When you want to fire an event no matter how a process exits: