Update README.md

Author: Josh Holtz

README.md

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 # JSONAPI - iOS
 
+[![Build Status](https://travis-ci.org/joshdholtz/jsonapi-ios.png?branch=master)](https://travis-ci.org/joshdholtz/jsonapi-ios)
+
 A library for loading data from a [JSON API](http://jsonapi.org) datasource. Parses JSON API data into models with support for auto-linking of resources and custom model classes.
 
 ### Features