Update README.md

Change sbromberger to correct JuliaGraphs link

Author: matbesancon

README.md

@@ -1,8 +1,8 @@
 # StaticGraphs
 
-[![Build Status](https://travis-ci.org/sbromberger/StaticGraphs.jl.svg?branch=master)](https://travis-ci.org/sbromberger/StaticGraphs.jl)
+[![Build Status](https://travis-ci.org/JuliaGraphs/StaticGraphs.jl.svg?branch=master)](https://travis-ci.org/JuliaGraphs/StaticGraphs.jl)
 
-[![codecov.io](http://codecov.io/github/sbromberger/StaticGraphs.jl/coverage.svg?branch=master)](http://codecov.io/github/sbromberger/StaticGraphs.jl?branch=master)
+[![codecov.io](http://codecov.io/github/JuliaGraphs/StaticGraphs.jl/coverage.svg?branch=master)](http://codecov.io/github/JuliaGraphs/StaticGraphs.jl?branch=master)
 
 Memory-efficient, performant graph structures optimized for large networks. 
 Uses [LightGraphs](https://github.com/JuliaGraphs/LightGraphs.jl).