Remove letters-related code (#175)

This deletes a big ol' chunk of code related to letters. It's not everything—there are still a few things that might be tied to sms/email—but it's the the heart of letters function. SMS and email function should be untouched by this.

Areas affected:

- Things obviously about letters
- PDF tasks, used for precompiling letters
- Virus scanning, used for those PDFs
- FTP, used to send letters to the printer
- Postage stuff

tests/app/template/test_rest_history.py

@@ -5,7 +5,6 @@ from flask import url_for
 
 from app.dao.templates_dao import dao_update_template
 from tests import create_admin_authorization_header
-from tests.app.db import create_letter_contact
 
 
 def test_template_history_version(notify_api, sample_user, sample_template):
@@ -99,22 +98,3 @@ def test_all_versions_of_template(notify_api, sample_template):
             assert json_resp['data'][1]['content'] == newer_content
             assert json_resp['data'][1]['updated_at']
             assert json_resp['data'][2]['content'] == old_content
-
-
-def test_update_template_reply_to_updates_history(client, sample_letter_template):
-    auth_header = create_admin_authorization_header()
-    letter_contact = create_letter_contact(sample_letter_template.service, "Edinburgh, ED1 1AA")
-
-    sample_letter_template.reply_to = letter_contact.id
-    dao_update_template(sample_letter_template)
-
-    resp = client.get(
-        '/service/{}/template/{}/version/2'.format(sample_letter_template.service_id, sample_letter_template.id),
-        headers=[auth_header]
-    )
-    assert resp.status_code == 200
-
-    hist_json_resp = json.loads(resp.get_data(as_text=True))
-    assert 'service_letter_contact_id' not in hist_json_resp['data']
-    assert hist_json_resp['data']['reply_to'] == str(letter_contact.id)
-    assert hist_json_resp['data']['reply_to_text'] == letter_contact.contact_block