replace travis, appveyor, and codecov badges with anologous from shie…

…lds.io (badges seem to appear faster and are more up to date) [ci skip]

README.md

@@ -1,8 +1,8 @@
 # scope_guard
 
-[![Build Status](https://travis-ci.org/ricab/scope_guard.svg?branch=master)](https://travis-ci.org/ricab/scope_guard)
-[![Build status](https://ci.appveyor.com/api/projects/status/nv4eyoxlhfxvgk96/branch/master?svg=true)](https://ci.appveyor.com/project/ricab/scope-guard/branch/master)
-[![codecov](https://codecov.io/gh/ricab/scope_guard/branch/master/graph/badge.svg)](https://codecov.io/gh/ricab/scope_guard)
+[![Build Status](https://img.shields.io/travis/ricab/scope_guard.svg)](https://travis-ci.org/ricab/scope_guard)
+[![Build status](https://img.shields.io/appveyor/ci/ricab/scope-guard.svg)](https://ci.appveyor.com/project/ricab/scope-guard/branch/master)
+[![codecov](https://img.shields.io/codecov/c/github/ricab/scope_guard.svg)](https://codecov.io/gh/ricab/scope_guard)
 
 [![GitHub license](https://img.shields.io/github/license/ricab/scope_guard.svg)](https://github.com/ricab/scope_guard/blob/master/LICENSE)
 [![GitHub release](https://img.shields.io/github/release/ricab/scope_guard/all.svg)](https://github.com/ricab/scope_guard/releases)