Add a "Training" page with external links

I collected the external links into the "Education & Training" section, and updated the links a bit so that visitors can navigate to that page.

• In the "Discover Our Services" box, the "Education & Training" button goes directly to the specific page for education and training. (The other buttons still navigate to the different sections of the "Services" page.)
• In the "Services" page, the "Education & Training" box has a "More..." button that goes to the specific page for education and training.
• The "Education & Training" page includes:
  • Small overview of what the education and training component does
  • A list of upcoming workshops (will be automatically updated to show events that are (a) in the future and (b) type = workshop
  • A list of external links with some explanation as to why they are useful
  • "Email us" links

In addition, I managed to squash #162 (closed) along the way.

Closes: #155 (closed), #162 (closed)