Auto merge of #220 - atouchet:travis, r=Manishearth

Update Travis CI URL

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Author: bors-servo

README.md

@@ -1,6 +1,6 @@
 # string-cache
 
-[![Build Status](https://travis-ci.org/servo/string-cache.svg?branch=master)](https://travis-ci.org/servo/string-cache)
+[![Build Status](https://travis-ci.com/servo/string-cache.svg?branch=master)](https://travis-ci.com/servo/string-cache)
 
 [Documentation](https://docs.rs/string_cache/)