Fixes and Improvements for communication layer

Various fixes in the communication layer of Eddie. This version of the code (for the communication part) is the functionally same used in the demos.

communication/include/CoapClient.h

@@ -58,6 +58,16 @@ public:
         std::unique_lock<decltype(m_)> lock(m_);
         c_.erase(k);
     }
+
+    void delete_all() {
+        std::unique_lock<decltype(m_)> lock(m_);
+        c_.erase(c_.begin(), c_.end());
+    }
+
+    int empty() {
+        std::unique_lock<decltype(m_)> lock(m_);
+        return c_.empty();
+    }
 };
 
 template<class Key, class Value>
@@ -131,6 +141,17 @@ public:
 
         return return_list;
     }
+
+    void delete_all() {
+        std::unique_lock<decltype(m_)> lock(m_);
+        s_.erase(s_.begin(), s_.end());
+        mm_.erase(mm_.begin(), mm_.end());
+    }
+
+    int empty() {
+        std::unique_lock<decltype(m_)> lock(m_);
+        return mm_.empty();
+    }
 };