Add bitcoinjs-lib dependency

[coreyphillips]

This PR:

• Adds bitcoinjs-lib as a dependency.
• Replaces the fetch request to https://runkit.io/overtorment/output-script-to-address/branches/master/ in the script2address method with the bitcoinjs-lib implementation.

[Overtorment]

this dependency was omitted on purpose so the necessary functions would be injected by outer code, see this.injectedScript2address in your case

[coreyphillips]

If you would prefer to stick to a bring-your-own-method approach, I would suggest removing the fetch request completely and simply require the injectedScript2address method upon instantiation.

The same can be said for the decodeInvoice method here. I would be happy to open a PR making the changes if you would prefer that approach.

[Overtorment]

eventually, yes, but not now.

consider, theres an example app in this repo, and i dont really want to mess with it to wire the socket to it so it can get data from electrum, crypto for bitcoinjs, rn-nodeify, all that.