Migrate import statements and macros to Rust 2018.

src/ctap/storage.rs

@@ -20,7 +20,12 @@ use crate::ctap::status_code::Ctap2StatusCode;
 use crate::ctap::{key_material, USE_BATCH_ATTESTATION};
 use crate::embedded_flash::{self, StoreConfig, StoreEntry, StoreError};
 use alloc::string::String;
+#[cfg(any(test, feature = "ram_storage", feature = "with_ctap2_1"))]
+use alloc::vec;
 use alloc::vec::Vec;
+use arrayref::array_ref;
+#[cfg(feature = "with_ctap2_1")]
+use cbor::cbor_array_vec;
 use core::convert::TryInto;
 use crypto::rng256::Rng256;