Merge pull request #21 from gvwilson/master

Creating badges for a dozen new instructors.
Importing four more blog posts from the old site
Adding some date/time sanity checks to the blog preprocessor, and fixing broken blog entries found as a result
Merge pull request #23 from gvwilson/sanity-checks-on-blog-posts

Adding some date/time sanity checks to the blog preprocessor, and fixing...
Merging updates to blog posts