R1:1abd74459fdc

Make view/sign page the primary Legalpad page

Summary:
- Makes the "legal document" page the main page.
- Links to the "manage" page.
- The "manage" operation now requires CAN_EDIT.
- Modernize some crumbs and such.

Test Plan: {F170213}

Reviewers: chad

Reviewed By: chad

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D9733