Free dnsServer object correctly; provide debugging message if it fails to start correctly. (#81)

* Free dnsServer object correctly; provide debugging message if it fails to start correctly.

* Update library.json

Increment version.

* Increment version.

Increment version.

* Revert "Increment version."

This reverts commit 225a31c927b76d1af419c2cba2dc5a20e1f59c42.

* Revert "Update library.json"

This reverts commit d5f5b96f25a2795c7756c6d47097befa9558e56e.

* Increment version to 0.24.

library.json

@@ -9,5 +9,5 @@
   },
   "frameworks": "arduino",
   "platforms": ["espressif8266", "espressif32"],
-  "version": "0.23"
+  "version": "0.24"
 }

library.properties

@@ -1,5 +1,5 @@
 name=ESP Async WiFi Manager
-version=0.23
+version=0.24
 author=alanswx
 maintainer=alanswx
 sentence=ESP8266 and ESP32 Async WiFi Connection manager with fallback web configuration portal