Leading and trailing days should be considered part of the month in month view.

Summary: Closes T8177, Leading and trailing days should be considered part of the month in month view.

Test Plan: Open month view, no days should be empty unless they don't have events. Modify query, make sure month view still obeys query.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin, epriestley

Maniphest Tasks: T8177

Differential Revision: https://secure.phabricator.com/D12834