Add Statemint Genesis Values (#817) (#905)

* Add Statemint Genesis Values (#817)

* add some docs to genesis scripts

* move statemint test chainspec

* add initial (draft) version of statemint chain spec

* adjust genesis value script

* add Statemint genesis Aura keys

* add bootnodes to statemint-genesis spec

* Add checks, debug and doc (#790)

* Add checks, debug and doc

* Update scripts/generate_genesis_value.sh

Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>

* Update scripts/generate_genesis_value.sh

Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>

Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>

* default to official shell rpc endpoint for genesis values

* remove statemint test chain spec

* add Statemint chain spec and genesis values

* sort statemint genesis values

* some script docs adjustments

Co-authored-by: Chevdor <chevdor@users.noreply.github.com>

* cargo fmt

Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>
Co-authored-by: Chevdor <chevdor@users.noreply.github.com>