Change travis references to circleci in doc

CONTRIBUTING.md

@@ -42,7 +42,7 @@ Your pull request must:
 
  * Follow OpenLayers's coding style.
 
- * Pass the integration tests run automatically by the Travis Continuous
+ * Pass the integration tests run automatically by the CircleCI Continuous
    Integration system.
 
  * Address a single issue or add a single item of functionality.

DEVELOPING.md

@@ -5,9 +5,9 @@
 You will obviously start by
 [forking](https://github.com/openlayers/openlayers/fork) the OpenLayers repository.
 
-### Travis CI
+### CircleCI
 
-The Travis CI hook is enabled on the Github repository. This means every pull request
+The CircleCI hook is enabled on the Github repository. This means every pull request
 is run through a full test suite to ensure it compiles and passes the tests. Failing
 pull requests will not be merged.
 

README.md

@@ -62,4 +62,4 @@ Please see our guide on [contributing](CONTRIBUTING.md) if you're interested in
 - Need help? Find it on [Stack Overflow using the tag 'openlayers'](http://stackoverflow.com/questions/tagged/openlayers)
 - Follow [@openlayers](https://twitter.com/openlayers) on Twitter
 
-[![Build Status](https://travis-ci.org/openlayers/openlayers.svg?branch=master)](https://travis-ci.org/openlayers/openlayers)
+[![CircleCI](https://circleci.com/gh/openlayers/openlayers/tree/master.svg?style=svg)](https://circleci.com/gh/openlayers/openlayers/tree/master)