Add publish date and author to posts

[Aloso]

Fixes issue #308

This is what it looks like:

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @aturon (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see the contribution instructions for more information.

[rust-highfive]

Warning

• Pull requests are usually filed against the gh-pages branch for this repo, but this one is against master. Please double check that you specified the right target!

[Aloso]

I now also added publish date and author(s) to all blog entries. They are directly under the title, like before. It is formatted like

Jan. 21, 2016 • The Rust Core Team

[steveklabnik]

Thank you, this looks great!

Same question about the git metadata though!

[Aloso]

The wrong metadata was a mistake.

[steveklabnik]

Thank you!