remove gocoverage

README.md

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-[![Build Status](https://travis-ci.org/goanywhere/rex.svg?branch=master)](https://travis-ci.org/goanywhere/rex) [![Coverage](http://gocover.io/_badge/github.com/goanywhere/rex?0)](http://gocover.io/github.com/goanywhere/rex) [![GoDoc](https://godoc.org/github.com/goanywhere/rex?status.svg)](http://godoc.org/github.com/goanywhere/rex)
+[![Build Status](https://travis-ci.org/goanywhere/rex.svg?branch=master)](https://travis-ci.org/goanywhere/rex) [![GoDoc](https://godoc.org/github.com/goanywhere/rex?status.svg)](http://godoc.org/github.com/goanywhere/rex)
 
 Rex is a library for modular web development in [Go](http://golang.org/), designed to work directly with net/http.