* reserved peers: lock them, use a hashset, and provide to networkcontext
* adding and removing reserved peer service API
* add NonReservedPeerMode, and setters in host
* setting non reserved mode, restriction accepted connections
* implement RPC apis
* fix deadlock
* fix rpc tests
* 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.