Filling-in optional fields of TransactionRequest... (#1305)

* More meaningful errors when sending transaction

* Fixing returned value

* Consolidating all RPC error codes

* Fixed loosing peers on incoming connections. (#1293)

* Deactivate peer if it has no new data

* Fixed node table timer registration

* Fixed handshake timeout expiration

* Extra trace

* Fixed session count calculation

* Only deactivate incapable peers in ChainHead state

* Timer registration is not needed

* x64 path

* firewall rules

* Fix read-ahead bug.

Re-ahead 8 bytes rather than 3 to ensure large blocks import fine.

* Refactor to use a const.

* Update README.md

* Gas price statistics. (#1291)

* Gas price statistics.

Affects eth_gasPrice.
Added ethcore_gasPriceStatistics.

Closes #1265

* Fix a bug in eth_gasPrice

* Fix tests.

* Revert minor alteration.

* Tests for gas_price_statistics.

- Tests;
- Additional infrastructure for generating test blocks with
transactions.

* Key load avoid warning (#1303)

* avoid warning with key

* fix intendations

* more intendation fix

* ok() instead of expect()

* Filling-in optional fields of TransactionRequest.

* Adding reference to miner