Feature/quality of life enhancements

Fixes #366, #367, and #368.

 This PR makes a variety of quality of life improvements.

* There's now a /blog/<username> api,
      which is used by the newly AJAXified
      participants page to quickly and
      asynchronously load blog post counts.

* URLs should be more discoverable now,
      with path names matching page titles.
      e.g. /participants instead of /checkblogs.
      Where possible, the old urls are also supported
      to avoid dead links.

* The instructor is now fully populated from
      the site.yaml file, rather than the previous
      implementation which had Remy specific stuff
      hardcoded.

* The TA section of the course information box on
      the syllabus will now be filled out from
      site.yaml automatically, and hidden if there
      isn't one.

* Enabled PACE loading bars on the participants page.

* Turned on workzeug threads when in local dev mode.