1. Use std::is_standard_layout and std::is_trivially_copyable instead of std::is_pod for KV byte-wise serialization, which fixes compile issue for Boost UUIDs
2. Removed reimplementation of std::hash for boost::uuids::uuid
3. Removed << operator overload for crypto::secret_key
4. Removed instances in code where private view key was dumped to the log in plaintext
Release version of #9450, containing C++14 modified assertions
Partially implements #74.
Securely erases keys from memory after they are no longer needed. Might have a
performance impact, which I haven't measured (perf measurements aren't
generally reliable on laptops).
Thanks to @stoffu for the suggestion to specialize the pod_to_hex/hex_to_pod
functions. Using overloads + SFINAE instead generalizes it so other types can
be marked as scrubbed without adding more boilerplate.
