Clean up front page UI and video elements, remove cruft [OPEN-407, OPEN-358]

Ref: https://openedx.atlassian.net/secure/attachment/14110/default-view-audit.pdf, https://openedx.atlassian.net/browse/OPEN-407

- [x] Change "Terms of Service & Honor Code" to remove "honor code" - doesn't make sense for everyone, and the page is called "tos.html" and doesn't say Honor Code in the header.
- [x] Remove reference to old marketing video
- [x] Strike Jobs, News pages
- [x] Change "Vision" header on default About page to "About"
- [ ] Change bright blue default background (index page) to something... better
- [ ] Change very light grey default background (course detail page, find course logged in view) to something better (same color as above, probably)
- [ ] Remove any cruft encountered:
    - [x] lms/templates/contact.html
    - [x] lms/templates/edx-legacy.html
- [ ] Change "EXPLORE FREE COURSES FROM LEADING UNIVERSITIES." text on the "Find Courses" page
@sarina that should be correct. We use footer.html, footer-edx-new.html, and theme-footer.html as an override.