attempt at okfn/okfn.github.com#103

So... here's my take on adding an author image (and perhaps other stuff?) to a blog post.  It repurposes the list element from the /members page, changes the odd/even class cycling to simply odd, and sticks it under the post content, separated by an hr tag.

Liquid "for" and "if" logic on same line to remove blank lines that would otherwise be generated.

Because it is a largely cut/paste job, it might benefit from being made into an _include to be shared between a post and the /members page.