* 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.
* use bloomchain crate in blockchain module. remove obsole chainfilter submodule
* update database version to 6.0
* removed redundant line
* simple db migration
* make migration slightly more functional
* bloomchain migration
* migration version is just a single unsigned integer
* updated migration v6
* parity migration
* db migration
* removed hardcoded migration dir
* replace ptr::copy with clone_from_slice, removed potential endianess problem from trace/db.rs
* removed superfluous line
* blockchains log blooms config is not exposed any more