Homestyx hydra

R1:1599c56217a1

Add Pinboard Items to Timeline

Summary: This allows adding of pinboard items to a timeline. I'm hoping we can get this in for Maniphest (Pholio, Cover Image) and Macro (because, Macro), but unsure how to scalably do this. Anyways, here's the front end.

Test Plan:
Make some fake timeline items in UIExamples, test mobile, tablet, and desktop breakpoints.

{F4965798}

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D17950
Repository: R1 hydra
Commit Date: May 18 2017