Rename key module to piv (#277)

Now that the crate is named `yubikey` rather than `yubikey-piv`, it
makes more sense to call this module out as PIV-related functionality.

cli/src/commands/status.rs

@@ -4,7 +4,7 @@ use crate::terminal::STDOUT;
 use gumdrop::Options;
 use std::io::{self, Write};
 use termcolor::{ColorSpec, StandardStreamLock, WriteColor};
-use yubikey::{key::*, YubiKey};
+use yubikey::{piv::*, YubiKey};
 
 use crate::print_cert_info;
 

cli/src/lib.rs

@@ -20,7 +20,7 @@ use std::str;
 use subtle_encoding::hex;
 use termcolor::{ColorSpec, StandardStreamLock, WriteColor};
 use x509_parser::parse_x509_certificate;
-use yubikey::{certificate::Certificate, key::*, YubiKey};
+use yubikey::{certificate::Certificate, piv::*, YubiKey};
 
 /// Write information about certificate found in slot a la yubico-piv-tool output.
 pub fn print_cert_info(