Handled ajax request crash after session timeout

process_response refers request.horizon in case of ajax
request, but this attribute was not set on session timeout.
redirection to previous page was not sent.

IMPORTANT NOTE:
After a session timeout, when logging back in the requested modal dialogue
is displayed in a static view page.

Change-Id: I793b1c0a4c51107d263de0fe144dca26f5216d7a
Closes-Bug: #1214812
Merge "Handled ajax request crash after session timeout"