Restricting query to return the displayed range

Summary: Ref T4393, Refactoring calendar query logic to only return at most what the query dates have specified

Test Plan: Query Calendar events for range May 1 - indefinite in month view, see events, scroll back to April, events should be absent, because April is out of range.

Reviewers: Blessed Reviewers, epriestley

Reviewed By: Blessed Reviewers, epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T4393

Differential Revision: https://secure.phabricator.com/D12728