Improve SEO for forum

[AndrewMagliozzi]

• [x] use this package: https://github.com/gadicc/meteor-sitemaps

We should also try to contribute our improvements back to Telescope upstream. See this ticket: https://github.com/TelescopeJS/Telescope/issues/355

We already did 'friendly URLs' for them, which is nice.

See this handy Blog post for what we ought to do:

https://gentlenode.com/journal/meteor-12-the-complete-guide-to-seo/20

All the google site map rules you never wanted to read:

• https://support.google.com/webmasters/answer/183668?hl=en&authuser=0&ref_topic=6080646&rd=1

[AndrewMagliozzi]

Here is a helpful tool from facebook to debut seo: https://developers.facebook.com/tools/debug/og/object?q=https%3A%2F%2Faboutadmissions.admithub.com

Note, we need to add the following:

• [x] add a robots.txt file
• [x] og:title [homepage] = "About Admissions: A free forum for college admissions advice"
• [x] dynamic title tags for each question in this format {{ question }} - {{ categories }}
  • see https://github.com/DerMambo/ms-seo#dynamic-seo-data
• [x] og:image = [our logo once Jordan submits it]
• [x] meta:description = "AboutAdmissions is a free and open forum for college admissions advising. Ask us anything about admissions and a current or former admissions dean, director, or officer will answer your question for free."

[AndrewMagliozzi]

once we have a sitemap, I'll submit it to the relevant search engines...

[yourcelf]

All parts implemented. Notes:

• Default title is "{{ title }}: {{ tagline }}" where title and tagline are defined in soft settings on the web.
• Meta descriptions, og:image, etc. are all defined in soft settings on the web.
• settings.xml shows all post lists and categories, as well as the top unique 100 each of "top", "best", and "new".
• robots.txt only lists path to sitemap.xml, and nothing else. It's autodefined by gadicc/meteor-sitemaps.