Phase 1 of repo reorg (#719)

* Remove unneeded script

* Rename Substrate Demo -> Substrate

* Rename demo -> node

* Build wasm from last rename.

* Merge ed25519 into substrate-primitives

* Minor tweak

* Rename substrate -> core

* Move substrate-runtime-support to core/runtime/support

* Rename/move substrate-runtime-version

* Move codec up a level

* Rename substrate-codec -> parity-codec

* Move environmental up a level

* Move pwasm-* up to top, ready for removal

* Remove requirement of s-r-support from s-r-primitives

* Move core/runtime/primitives into core/runtime-primitives

* Remove s-r-support dep from s-r-version

* Remove dep of s-r-support from bft

* Remove dep of s-r-support from node/consensus

* Sever all other core deps from s-r-support

* Forgot the no_std directive

* Rename non-SRML modules to sr-* to avoid match clashes

* Move runtime/* to srml/*

* Rename substrate-runtime-* -> srml-*

* Move srml to top-level