(wip) Post-FMD updates

Implement post-FMD to the anniversary site.

#### What's the plan?
Add in links to projects like Salaries & TribTalk. Switch out anniversary logo without FMD. Change copy in second paragraph. Social copy updates for FB, Twitter & email.

#### What's this PR do?


#### 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:
* [x] switch out anniversary logo when receive from art
* [x] update 2nd paragraph copy when receive from membership
* [x] update social copy when receive from membership

#### Has the relevant documentation/wiki been updated?

#### Technical debt note