R1:5284053c0e30

Add X-Frame-Options for all response

Summary:
we use to only add X-Frame-Options for AphrontWebpageResponse.
There some security concern about it. Example of a drag-drop attack:
http://sites.google.com/site/tentacoloviola/. The fix is to add it to
all AphrontResponse.

Test Plan:
View page which disalble this option still works (like the
xhpast tree page); verify that the AphrontAjaxResponse contains the
X-Frame-Options in the header.

Reviewers: epriestley, benmathews

Reviewed By: epriestley

CC: nh…