Began backend implementation for a profile setting that will determine whether

to automatically archive a review request when posted.

This included adding a publish_and_archive BooleanField to the

AccountSettingsForm in reviewboard/accounts/pages.py, which is initially set

to False. publish_and_archive was also added to the Profile in

reviewboard/accounts/models.py. Lastly, publish_and_archive was also added to

reviewboard/accounts/accounts.py in the js_user_session_info() function.

A series of tests were also implmeneted to ensure that the AccountSettingsForm

was initialized, loaded, and saved properly and that it correctly identified

invalid inputs. These tests were added to

reviewboard/accounts/test/test_account_settings_form.py.
All previous passing pytests still passed.