Added optional serde support, including an example in the README

[cisaacson]

Here is the PR for the serde feature. I added a simple example using bincode in the README. There is no test, I could do that easily but it would mean adding another dev dependency, not sure if you wanted that in the codebase.

The version has not been changed, that should be done if you decide this to put it in a release.

[WaDelma]

bors r+

Sorry for leaving this hanging.

[WaDelma]

bors r+

lets try again :D

[WaDelma]

I seem to still be on list of people bors responds to. Is it dead or what has happened?

[cisaacson]

Thanks, I hope it is useful to others. Let me know if you need me to do anything else.