(wip) Post-FMD updates

Implement post-FMD to the anniversary site.

#### What's the plan?
[for PRs that haven't been fully implemented yet]

#### What's this PR do?
Adds in links to projects like Salaries & TribTalk. Switches out anniversary logo without FMD. Changes copy in second paragraph. Social copy updates for FB, Twitter & email.

#### Why are we doing this? How does it help us?
Allows us to use the 5th anniversary site for other campaigns.

#### How should this be manually tested?
`bundle exec middleman`
Check links, check for correct logo, check for correct copy updates.

#### What are the relevant tickets?
Sprint task: https://basecamp.com/1866004/projects/1175549/todos/138779199

#### Next steps?

#### Smells?

#### TODOs:
* [ ] switch out anniversary logo when receive from art
* [ ] update 2nd paragraph copy when receive from membership
* [ ] update social copy when receive from membership

#### Has the relevant documentation/wiki been updated?

#### Technical debt note