Add "View All" header buttons to user and project feed boxes

Summary:
Fixes T12762. Currently, there's no way to get from these boxes into generaly history in Feed, and it isn't clear that the operation is possible.

For now, add some simple links. See T12762 for future work.

Test Plan:

• Viewed user profles, saw "View All".
• Viewed project profiles, saw "View All".

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T12762

Differential Revision: https://secure.phabricator.com/D18030