Update thread timestamp on draft creation.

Fixes #1055
Closes #2909

// FREEBIE

src/org/thoughtcrime/securesms/ConversationActivity.java

@@ -895,7 +895,7 @@ public class ConversationActivity extends PassphraseRequiredActionBarActivity
           if (threadId == -1) threadId = threadDatabase.getThreadIdFor(getRecipients(), thisDistributionType);
 
           draftDatabase.insertDrafts(new MasterCipher(thisMasterSecret), threadId, drafts);
-          threadDatabase.updateSnippet(threadId, drafts.getSnippet(ConversationActivity.this), Types.BASE_DRAFT_TYPE);
+          threadDatabase.updateSnippet(threadId, drafts.getSnippet(ConversationActivity.this), System.currentTimeMillis(), Types.BASE_DRAFT_TYPE);
         } else if (threadId > 0) {
           threadDatabase.update(threadId);
         }

src/org/thoughtcrime/securesms/database/ThreadDatabase.java

@@ -130,8 +130,10 @@ public class ThreadDatabase extends Database {
     notifyConversationListListeners();
   }
 
-  public void updateSnippet(long threadId, String snippet, long type) {
+  public void updateSnippet(long threadId, String snippet, long date, long type) {
     ContentValues contentValues = new ContentValues(3);
+
+    contentValues.put(DATE, date - date % 1000);
     contentValues.put(SNIPPET, snippet);
     contentValues.put(SNIPPET_TYPE, type);
     SQLiteDatabase db = databaseHelper.getWritableDatabase();