Cleanups and fixes for the communication layer

Remove no longer used code and add include guards. Details are in the commit messages.

Signed-off-by: Stefan Schmidt stefan.schmidt@huawei.com

communication/include/CoapClient.h

@@ -56,7 +56,6 @@ public:
 
     void erase(Key const &k) {
         std::unique_lock<decltype(m_)> lock(m_);
-        Value elem = this->get(k);
         c_.erase(k);
     }
 };