Use a single flow to send a transaction for remote and local nodes

[adambabik]

Problem

It is described in this comment.

The problem is that having two separate flows to send a transaction introduces subtle differences that may be hard to debug, maintain and can lead to inconsistencies.

Implementation

Create a single flow in status-go to send all transactions via eth_sendRawTransaction regardless which node is used.

Acceptance Criteria

1. There is a single flow to send a transaction,
2. The whole code related to gas estimation, getting a nonce etc. is in one place,
3. Sending a transaction works with local and remote nodes.

[status-open-bounty]

Balance: 0.000000 ETH
Tokens: SNT: 870.00
Contract address: 0x9ee854507d03f592ec5bfe47e214a34f6e884c16
Network: Mainnet
Paid to: dshulyak
Visit https://openbounty.status.im to learn more.