Get rid of Page.meta

[mythmon]

It was convenient for reading in the header data, but now it complicates the external interface. Everything should be a property of Page.

How can it still support arbitrary metadata being passed if this happens?

[mythmon]

Closing as wontfix. I've decided to keep Page.meta around, because of its convenience. To simplify the external interface, I have added a getattr method that will use values from meta if the name is not found in Page.