Updates README.md with svg badge

Author: sobolevn

README.md

@@ -2,7 +2,7 @@
 
 > SQL Schema migration tool for [Go](http://golang.org/). Based on [gorp](https://github.com/go-gorp/gorp) and [goose](https://bitbucket.org/liamstask/goose).
 
-[![Build Status](https://travis-ci.org/rubenv/sql-migrate.svg?branch=master)](https://travis-ci.org/rubenv/sql-migrate) [![GoDoc](https://godoc.org/github.com/rubenv/sql-migrate?status.png)](https://godoc.org/github.com/rubenv/sql-migrate)
+[![Build Status](https://travis-ci.org/rubenv/sql-migrate.svg?branch=master)](https://travis-ci.org/rubenv/sql-migrate) [![GoDoc](https://godoc.org/github.com/rubenv/sql-migrate?status.svg)](https://godoc.org/github.com/rubenv/sql-migrate)
 
 Using [modl](https://github.com/jmoiron/modl)? Check out [modl-migrate](https://github.com/rubenv/modl-migrate).