Rearranging names and file structure for Celluloid support, with the idea that it will be a preferred way for people to interact with Telehash and thus should be a top-level concept.

- Move Telehashi module classes to Telehash::Core
- Move lib/telehash/* to lib/telehash/core/*
- Move specs/*_spec.rb to specs/core/*_spec.rb
add core specs back
move RawPacket to instead be a type 'Raw' under the Packet submodule