Assign the WiFi MAC address as the mobile's serial number.

[jnadeu]

Currently, the mobile phone serial number is not collected, but the WiFi MAC address is assigned as if it were the mobile phone serial number.

It would be necessary to see how to collect the serial number of the mobile phone.

https://github.com/eReuse/eReuseApp-Android-Java/blob/07adbb78503f4ddcb88cf15e1dc7bd355b038d77/app/src/main/java/com/example/ereuseapp/MainActivity.java#L110