Merge pull request #1270 from gitter-badger/gitter-badge

Add a Gitter chat badge to README.md

README.md

@@ -1,5 +1,7 @@
 ## Ethereum C++ Client.
 
+[![Join the chat at https://gitter.im/ethereum/cpp-ethereum](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/ethereum/cpp-ethereum?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+
 By Gav Wood et al, 2013, 2014, 2015.
 
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