docs(README): Add david-dm.org devDependencies status image

Caitlin Potter · pkozlowski-opensource · commit 473838677ff2 · 2013-09-27T09:26:57.000+02:00
diff --git a/README.md b/README.md
@@ -2,7 +2,7 @@
 
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-[![Build Status](https://secure.travis-ci.org/angular-ui/bootstrap.png)](http://travis-ci.org/angular-ui/bootstrap)
+[![Build Status](https://secure.travis-ci.org/angular-ui/bootstrap.png)](http://travis-ci.org/angular-ui/bootstrap) [![devDependency Status](https://david-dm.org/angular-ui/bootstrap/dev-status.png?branch=master)](https://david-dm.org/angular-ui/bootstrap#info=devDependencies)
 
 ## Demo
 
