debian: update debian/NEWS and debian/changelog

Plagiarize my upstream summary for debian, and mention the new
upgrade.

debian/NEWS

@@ -1,3 +1,13 @@
+notmuch (0.19-1) experimental; urgency=medium
+
+  * This release of notmuch again requires a non-reversable database
+    upgrade to support database features. This upgrade will happen on
+    the first run of 'notmuch-new' after updating. Notmuch will backup
+    your tags for your before doing the upgrade, but it never hurts to
+    make your own backup with notmuch dump.
+
+ -- David Bremner <bremner@debian.org>  Fri, 14 Nov 2014 20:34:55 +0100
+
 notmuch (0.18~rc0-1) experimental; urgency=low
 
   * This release of notmuch requires a non-reversable database upgrade

debian/changelog

@@ -1,6 +1,14 @@
 notmuch (0.19-1) experimental; urgency=medium
 
-  * New upstream release
+  * New upstream release.
+    - Improvements to reliability of 'notmuch dump' and the error
+    handling for 'notmuch insert'.
+    - The new 'notmuch address' command is intended to make searching
+    for email addresses more convenient.
+    - At the library level the revised handling of missing messages
+    fixes at least one bug in threading.
+    - Interface improvements to the emacs interface, most notably the
+    ability to bindkeyboard shortcuts to saved searches.
 
  -- David Bremner <bremner@debian.org>  Fri, 14 Nov 2014 19:34:12 +0100