Add feature: remove service (#17)

* Get service handles on server start

* remove service + indicate service changed

* Reset gatt services when no connections active and services changed.

* NimBLEServer::createService can now be used any time and will send service changed
indication if server was already active.

* Add ability to remove advertised serviceUUIDS

* Adds addService() method to server to be allow user to re-add a service previously removed

* Add destructior to NimBLEServer, NimBLEService and NimBLECharacteristic to release allocated resources.

src/NimBLEService.h

@@ -57,6 +57,7 @@ public:
 private:
     NimBLEService(const char* uuid, uint16_t numHandles, NimBLEServer* pServer);
     NimBLEService(const NimBLEUUID &uuid, uint16_t numHandles, NimBLEServer* pServer);
+    ~NimBLEService();
 
     friend class          NimBLEServer;
     friend class          NimBLEDevice;
@@ -65,7 +66,8 @@ private:
     NimBLEServer*         m_pServer;
     NimBLEUUID            m_uuid;
     uint16_t              m_numHandles;
-
+    ble_gatt_svc_def*     m_pSvcDef;
+    uint8_t               m_removed;
     std::vector<NimBLECharacteristic*> m_chrVec;
 
 }; // NimBLEService