Bastian Köcher authored Jan 22, 2020 and Sergey Pepyakin committed Jan 22, 2020

This moves the wasm-allocator (`FreeingBumpHeapAllocator`) into its own
crate `sp-allocator`. This new crate can theoretically provide multiple
different allocators. Besides moving the allocator, this pr also makes
`FreeingBumpHeapAllocator` compile on `no_std`.