Remove go-ethereum dependency

[igor-sirotin]

Rationale

Historically, status-go was a "geth wrapper", but it's not anymore for quite some time. We were heavily based on go-ethereum: we were running a node and used Whisper protocol for messaging. For many reasons a fork was created.

This fork as of today is 8 commits ahead of, 2844 commits behind ethereum/go-ethereum:master:

The fork has serious several security issues and vulnerabilities.

Note

Perhaps we won't be able to remove the dependency completely.
geth contains a lot of handy functions and structs for web3 development.
Yet we should at least minimise it's usage as much as possible.

Dependencies to be replaced

On the other side, there's no big reason to actually still have go-ethereum as dependency. Below we will gather the list of how geth is used in status-go and alternatives for each usecase.

Use case	Proposed Alternative	Done
Keystore
JSON-RPC server	https://github.com/gorilla/rpc
log	zap.Logger	✅