* Use upstream rocksdb
…by way of https://github.com/paritytech/parity-common/pull/257 by @ordian.
* Hint at how `parity db reset` works in the error message
* migration-rocksdb: fix build
* Cargo.toml: use git dependency instead of path
* update to latest kvdb-rocksdb
* fix tests
* saner default for light client
* rename open_db to open_db_light
* update to latest kvdb-rocksdb
* moar update to latest kvdb-rocksdb
* even moar update to latest kvdb-rocksdb
* use kvdb-rocksdb from crates.io
* Update parity/db/rocksdb/helpers.rs
* add docs to memory_budget division