Brings the blog, staff photos, other content into Jekyll

There are three main things going on here: the creation of templates for blog posts, moving the staff photos into a YAML file, and injecting that YAML data into the index.html template. This makes the site look ostensibly the same as the 18f.gsa.gov you see today.

For the blog: instead of using JS to pull post data out of tumblr's we're serving out the raw HTML stuffed into a jekyll template. I used `jekyll-import` to dump the html from the pots out of tumblr. The one caveat is that our tags list is currently linked to the respective archives on tumblr but, because Jekyll doesn't fully support tags (as far as I can tell) we can't link to those archives.

For the staff photos: I created a yaml file in the `_data` directory with an entry for each person. Right now the keys are just `name` and `full_name` but the super upshot in using this over copying and pasting new html is the slimmed down template code and the ability to extend out the ways we visualize our team.

The last piece that both of those above feed into is significantly simplified templates. This commit cuts more than 200 lines out of the index.html template and adds reusable templates for blog posts.