Remove (old) pkg badges (#656)

The badges don't show anymore and the links get redirected to the
general https://pkg.julialang.org/docs/ which isn't very useful.

Author: martinholters

README.md

@@ -3,12 +3,6 @@
 [![Build Status](https://travis-ci.org/JuliaLang/Compat.jl.svg?branch=master)](https://travis-ci.org/JuliaLang/Compat.jl)
 [![Build status](https://ci.appveyor.com/api/projects/status/github/JuliaLang/Compat.jl?branch=master)](https://ci.appveyor.com/project/quinnj/compat-jl/branch/master)
 
-[![Compat](http://pkg.julialang.org/badges/Compat_0.3.svg)](http://pkg.julialang.org/?pkg=Compat&ver=0.3)
-[![Compat](http://pkg.julialang.org/badges/Compat_0.4.svg)](http://pkg.julialang.org/?pkg=Compat&ver=0.4)
-[![Compat](http://pkg.julialang.org/badges/Compat_0.5.svg)](http://pkg.julialang.org/?pkg=Compat&ver=0.5)
-[![Compat](http://pkg.julialang.org/badges/Compat_0.6.svg)](http://pkg.julialang.org/?pkg=Compat&ver=0.6)
-[![Compat](http://pkg.julialang.org/badges/Compat_0.7.svg)](http://pkg.julialang.org/?pkg=Compat&ver=0.7)
-
 The **Compat** package is designed to ease interoperability between
 older and newer versions of the [Julia
 language](http://julialang.org/).  In particular, in cases where it is