Initial release

[MabezDev]

• Rename Device trait to BlockDevice, find a new name for the BlockDevice <=> embedded-io wrapper.
• embedded examples #17
• Move the device feature stuff to its own crate? #16
• Ensure it can build on stable
  • Update or remove usage of async iter
• Cut a block-device-driver release and PR some impls to hals
  • Should alignment be part of the base trait?
  • Waiting on aligned release for new release
• Remove the File::new_from_context API, it's easy to misuse: Remove new_from_context from the public API #28
• Writing to a file doesn't update the in memory representation of the file #19
• Invalid '..' entry in the second slot #12