Add readme

README.md

+
+# Summary
+
+This simple example lets you execute a http get request on [Transport Opendata](http://transport.opendata.ch/v1/)
+
+- This snippet use [unirest](http://unirest.io/java.html) for the http client
+
+## How to
+
+Build and run :
+
+```
+mvn clean package
+mvn exec:java
+```
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