Add data output to file

[carbontwelve]

The parsed date as well as whether the file is a draft are both computed variables that are core to the File object within Tapestry.

Both can be set by front matter, but also have sane defaults with date defaulting to the files last updated time stamp and draft defaulting to false.

The File entity within the database should reflect these.

[carbontwelve]

Same with pretty_permalink.