Introduce basic skeleton for Polkadot runtime. (#32)

* Introduce basic skeleton for Polkador runtime.

* Clean up the runtime skeleton.

* Make initial runtime skeleton compile.

* Compile polkadot-runtime both for Wasm ad native, allowing for testing and direct usage.

* More fleshing out on runtime.

* Update native support.

* Fix warning.

* Update gitignore

* Update path.

* Fix path.

* Remove accidentally committed files.

* Add wasm binaries.

* Fix test.

* Native storage support API.

* Add environmental module

* Add native environment to make native source-code compatible with wasm.

Also tests.

* Finish up & polish environment stuff.

* Avoid using reentrancy issues.

* Add some docs and a test.

* Remove unneeded function.

* Documentation

* Tweak docs

* Remove TODOs.

* Balance transfers + util methods.

* Rejig tests and ensure authorities are addressed consistently.

* Add marshaller for xfer function

* Transaction dispatch test.

* Minor fix.

* Add test for ser/de transaction.

* Add ser/de for header.

* Add tests for header ser/de

* Introduce basic block decoding/execution framework.

* Introduce block decoding/execution framework (p2)

* Big refactor.

* Split out joiner.

* Hide away support modules.

* Fix up wasm runtime.

* use externalities for chain_id

* Clean up (Test)Externalities.

* Repot and introduce keccak-256 external.

* Signing with crypto.

* fix unsafety hole in environmental using function

* Introduce Ed25519 crypto.

* Repotting.

* Add ed25519_verify external.

* Introduce Ed25519 verify as an external.

* fix unsafety hole around unwinding

* Compile fixes.

* use new environmental API

* Tests for ed25519 verify.

* Polish

* Introduce UncheckedTransaction & test.

* Implement basic block and tx processing

* Introduce static hex and valid signature for block test.

* Repot session.

* comments.

* Refactor and timestamp test

* Remove fluff

* Remove fluff.

* Staking eras and tests.

* Implement sessions.

* Polish

* Test sessions.

* Introduce better hashing.

- Blake2 for secure hashing
- XX for fast hashing

* Fix tests.

* Introduce staking.

* Tests for simple staking system.

* Build fix for wasm.

* Fix tests.

* Repotting and docs.

* Docs and licence.

* Documentation.

* Remove superfluous code.

* Remove dummy key.

* Remove other superfluous file.

* Optimise with swap_remove