Stop counting video hits (#1879)

This was taking a lot of resources (disk usage, IO time, etc) and not
really used by our users.  Dropped a bunch of things:

  - Hitcount tables
  - Code to increment them
  - Tasks to migrate/aggregate them
  - Sorting by views in the search page
Merge branch 'staging' into gh-1879
Removed old volunteer pages
Merge pull request #1906 from pculture/gh-1879

Gh 1879