Legalpad - allow for legalpad documents to be required to be signed for using Phabricator

Summary: Fixes T7159.

Test Plan:
Created a legalpad document that needed a signature and I was required to sign it no matter what page I hit. Signed it and things worked! Added a new legalpad document and I had to sign again!

Ran unit tests and they passed!

Logged out as a user who was roadblocked into signing a bunch of stuff and it worked!

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T7159

Differential Revision: https://secure.phabricator.com/D11759

resources/sql/autopatches/20150212.legalpad.session.1.sql

@@ -0,0 +1,5 @@
+ALTER TABLE {$NAMESPACE}_user.phabricator_session
+  ADD signedLegalpadDocuments BOOL NOT NULL DEFAULT 0;
+
+ALTER TABLE {$NAMESPACE}_legalpad.legalpad_document
+  ADD requireSignature BOOL NOT NULL DEFAULT 0;

resources/sql/autopatches/20150212.legalpad.session.2.sql

@@ -0,0 +1,2 @@
+ALTER TABLE {$NAMESPACE}_legalpad.legalpad_document
+  ADD KEY `key_required` (requireSignature, dateModified);