Direct messages cannot be retrieved from mailservers when using status-go

[richard-ramos]

Using status-go only allows retrieval of public messages from mailservers.

When using murmur, it does retrieve both kind of messages. (Probably status-js is not sending the correct payload for direct messages.

Tip: compare what's being built with murmur against what status-go is doing in https://github.com/status-im/status-go/blob/develop/services/shhext/api.go

[richard-ramos]

Fixed by changing the minPow to 0