* 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
