Rename Peek and Poke to binary / cereal naming

[mgsloan]

We are already considering some breaking changes: #21

So this is a good time to consider other ones. While considering #31, it occurred to me that it may be convenient to make store's naming more consistent with binary. This would make it more straightforward to port code from binary to store. Some changes would need to change, but most of the time the custom implementations of put or get would not.

[mgsloan]

One downside is that it might imply that the ported code would have the same binary representation. We'd just need to document that it doesn't.

[mgsloan]

Closing this in favor of using this naming for architecture independent serialization - #36