Add serialization/deseriation support to event log

See bincode and serde_json for usage:
https://github.com/TyOverby/bincode

Fixes #1

src/lib.rs

@@ -1,6 +1,9 @@
 #![cfg_attr(feature = "unstable", feature(test))]
 pub mod log;
 pub mod historian;
-extern crate digest;
+extern crate generic_array;
 extern crate rayon;
+extern crate serde;
+#[macro_use]
+extern crate serde_derive;
 extern crate sha2;