Rust API: Low and high-level

[bochaco]

@bzee

Also, the high-level API provides Safe URLs and other helpful utilities and protocols, which is good to separate from the low-level part. Perhaps this needs to be put in a separate crate.

I agree, we have it, perhaps it’s time to move SafeUrl impl back to it: GitHub - maidsafe/sn_url. It was earlier discussed in Getting a safe:// url for a file