Add test coverage.

Author: ChrisHines

.travis.yml

@@ -1,11 +1,16 @@
 language: go
-
+sudo: false
 go:
-    - 1.0
-    - 1.1
-    - 1.2
-    - 1.3
-    - 1.4
-    - 1.5
-    - release
-    - tip
+  - 1.2
+  - 1.3
+  - 1.4
+  - 1.5
+  - 1.6
+  - tip
+
+before_install:
+  - go get github.com/mattn/goveralls
+  - go get golang.org/x/tools/cmd/cover
+
+script:
+  - goveralls -service=travis-ci

README.md

@@ -1,4 +1,7 @@
-[![GoDoc](https://godoc.org/github.com/go-stack/stack?status.svg)](https://godoc.org/github.com/go-stack/stack) [![Go Report Card](https://goreportcard.com/badge/go-stack/stack)](https://goreportcard.com/report/go-stack/stack) [![TravisCI](https://travis-ci.org/go-stack/stack.svg?branch=master)](https://travis-ci.org/go-stack/stack)
+[![GoDoc](https://godoc.org/github.com/go-stack/stack?status.svg)](https://godoc.org/github.com/go-stack/stack)
+[![Go Report Card](https://goreportcard.com/badge/go-stack/stack)](https://goreportcard.com/report/go-stack/stack)
+[![TravisCI](https://travis-ci.org/go-stack/stack.svg?branch=master)](https://travis-ci.org/go-stack/stack)
+[![Coverage Status](https://coveralls.io/repos/github/go-stack/stack/badge.svg?branch=master)](https://coveralls.io/github/go-stack/stack?branch=master)
 
 # stack