Remove the last parameter to copy_memory() since it no longer expects a length parameter.
Update README.md
Add pkgid attribute.
Stop using rustpkg for building and use make instead.

rustpkg still seems to have some issues, most significantly it can't handle
the rust-crypto-util crate all that well - doing a rustpkg install to fetch
this project results in an error trying to build rust-crypto-util.
Move rust-crypto-util to tools directory.

As far as rustpkg is concerned, rust-crypto-util is no longer part of the
project. This allows rustpkg install to fetch the project from a remote
location and to build it successfully.