Fix compiling warnings

[rafaeldelucena]

There's some annoying warnings in the compilation:

../../protocole/jsonclient.cpp: In member function ‘void JsonClient::onMessageReceived()’:             
../../protocole/jsonclient.cpp:77:12: warning: unused variable ‘len_signature’ [-Wunused-variable]            
     size_t len_signature = strlen(action_str.data());                                                                                                                                         
            ^~~~~~~~~~~~~

../../protocole/jsonclient.cpp: In member function ‘void JsonClient::onMessageReceived()’:             
../../protocole/jsonclient.cpp:77:12: warning: unused variable ‘len_signature’ [-Wunused-variable]            
     size_t len_signature = strlen(action_str.data());                                                                                                                                         
            ^~~~~~~~~~~~~ 

../../libFunq/dragndropresponse.cpp: In member function ‘virtual void DragNDropResponse::execute(int)’:
../../libFunq/dragndropresponse.cpp:154:48: warning: this statement may fall through [-Wimplicit-fallthrough=]
                                 Qt::NoModifier));                                                                                                                                             
                                                ^                                                                                                                                              
../../libFunq/dragndropresponse.cpp:156:9: note: here                                                                                                                                          
         case 5:  // and reply                                                                                                                                                                 
         ^~~~ 

../../libFunq/shortcutresponse.cpp: In member function ‘virtual void ShortcutResponse::execute(int)’:                                                                                          
../../libFunq/shortcutresponse.cpp:83:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]                                                                 
         for (uint i = 0; i < m_binding.count(); ++i) {                                                                                                                                        
                          ~~^~~~~~~~~~~~~~~~~~~                                                                                                                                                
../../libFunq/shortcutresponse.cpp:92:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]                                                                 
         for (uint i = 0; i < m_binding.count(); ++i) {                                                                                                                                        
                          ~~^~~~~~~~~~~~~~~~~~~ 

[rafaeldelucena]

Closed by #65