Enable library users to detect if a smart card doesn't support PIV (#476)

* Enable library users to detect if a smart card doesn't support PIV

Closes iqlusioninc/yubikey.rs#456.

* Avoid resetting the card if we fail to select PIV or fetch version/serial

src/lib.rs

@@ -49,6 +49,7 @@ mod mgm;
 mod mscmap;
 #[cfg(feature = "untested")]
 mod msroots;
+mod otp;
 pub mod piv;
 mod policy;
 pub mod reader;