Update README.md

Author: ChrisRackauckas

README.md

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+[![Build Status](https://travis-ci.org/JuliaDiffEq/ArrayInterface.jl.svg?branch=master)](https://travis-ci.org/JuliaDiffEq/ArrayInterface.jl)
+[![Build status](https://ci.appveyor.com/api/projects/status/s4vnsj386dyyv655?svg=true)](https://ci.appveyor.com/project/ChrisRackauckas/arrayinterface-jl)
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 # ArrayInterface.jl
 
 Julia has only recently reached v1.0 and the AbstractArray interface is still