Add codecov.io

Author: gliptak

.travis.yml

@@ -9,4 +9,7 @@ go:
   - 1.7
   - tip
 
-script: go test -race
+script: go test -race -coverprofile=coverage.txt -covermode=atomic
+
+after_success:
+  - bash <(curl -s https://codecov.io/bash)

README.md

@@ -1,5 +1,6 @@
 [![Build Status](https://travis-ci.org/DATA-DOG/go-sqlmock.png)](https://travis-ci.org/DATA-DOG/go-sqlmock)
 [![GoDoc](https://godoc.org/github.com/DATA-DOG/go-sqlmock?status.png)](https://godoc.org/github.com/DATA-DOG/go-sqlmock)
+[![codecov.io](https://codecov.io/github/DATA-DOG/go-sqlmock/branch/master/graph/badge.svg)](https://codecov.io/github/DATA-DOG/go-sqlmock)
 
 # Sql driver mock for Golang