Replace TravisCI with CircleCI

Author: nilium

.circleci/config.yml

@@ -0,0 +1,14 @@
+version: 2.1
+jobs:
+  build:
+    docker:
+      - image: circleci/golang:1.11
+        environment:
+          GO111MODULE: 'on'
+    working_directory: /tmp/codf
+    steps:
+      - checkout
+      - run: go build -v .
+      - run: go test -coverprofile=cover.out -covermode=atomic .
+      - run: go tool cover -func=cover.out
+      - run: bash <(curl -s https://codecov.io/bash) -f cover.out

.travis.yml

@@ -1,6 +1,6 @@
 codf
 ====
-[![Build Status](https://travis-ci.org/nilium/codf.svg?branch=master)](https://travis-ci.org/nilium/codf)
+[![CircleCI](https://circleci.com/gh/nilium/codf/tree/master.svg?style=svg)](https://circleci.com/gh/nilium/codf/tree/master)
 [![codecov](https://codecov.io/gh/nilium/codf/branch/master/graph/badge.svg)](https://codecov.io/gh/nilium/codf)
 [![Go Report Card](https://goreportcard.com/badge/go.spiff.io/codf)](https://goreportcard.com/report/go.spiff.io/codf)
 [![GoDoc](https://godoc.org/go.spiff.io/codf?status.svg)](https://godoc.org/go.spiff.io/codf)