rename all subclass diconnect() to disconnectServer()

Adafruit_MQTT_CC3000.h

@@ -81,7 +81,7 @@ class Adafruit_MQTT_CC3000 : public Adafruit_MQTT {
     return mqttclient.connected();
   }
 
-  bool disconnect() {
+  bool disconnectServer() {
     if (connected()) {
       return (mqttclient.close() == 0);
     }

Adafruit_MQTT_Client.cpp

@@ -33,7 +33,7 @@ bool Adafruit_MQTT_Client::connectServer() {
   return r != 0;
 }
 
-bool Adafruit_MQTT_Client::disconnect() {
+bool Adafruit_MQTT_Client::disconnectServer() {
   // Stop connection if connected and return success (stop has no indication of
   // failure).
   if (client->connected()) {

Adafruit_MQTT_Client.h

@@ -43,7 +43,7 @@ class Adafruit_MQTT_Client : public Adafruit_MQTT {
   {}
 
   bool connectServer();
-  bool disconnect();
+  bool disconnectServer();
   bool connected();
   uint16_t readPacket(uint8_t *buffer, uint8_t maxlen, int16_t timeout,
                       bool checkForValidPubPacket = false);

Adafruit_MQTT_FONA.h

@@ -51,7 +51,7 @@ class Adafruit_MQTT_FONA : public Adafruit_MQTT {
     return fona->TCPconnect(server, portnum);
   }
 
-  bool disconnect() {
+  bool disconnectServer() {
     return fona->TCPclose();
   }