Fix wallet connection on Mobile

[csillag]

We are relying on Metamask for the wallet connection. It works on desktop, but on (android) mobile:

• Firefox: can't detect Metamask
• Chrome can't detect Metamask
• Metamask's built-in browser: it can dedect Metamask, we can connect to the wallet, but switching the wallet to the desired network doesn't work.

So, all in all, currently we can't use a wallet on android at all. (Haven't even tested iOS)

[ptrus]

Works on iOS via the Metamask built-in browser.