Switch to Travis for CI

.travis.yml

@@ -0,0 +1,14 @@
+sudo: false
+language: ruby
+cache: bundler
+branches:
+  only:
+  - master
+rvm:
+  - 2.5
+  - 2.4
+  - 2.3
+before_install:
+  # https://github.com/travis-ci/travis-ci/issues/8978#issuecomment-354036443
+  - gem update --system
+  - gem install bundler

README.md

@@ -1,6 +1,6 @@
 # money
 
-[![Build Status](https://circleci.com/gh/Shopify/money.png?circle-token=88060f61185838446bb65723d96658bdd74ebb3c)](https://circleci.com/gh/Shopify/money) [![codecov](https://codecov.io/gh/Shopify/money/branch/master/graph/badge.svg)](https://codecov.io/gh/Shopify/money)
+[![Build Status](https://travis-ci.org/Shopify/money.svg?branch=master)](https://travis-ci.org/Shopify/money) [![codecov](https://codecov.io/gh/Shopify/money/branch/master/graph/badge.svg)](https://codecov.io/gh/Shopify/money)
 
 
 money_column expects a decimal 8,3 database field.