tack in one more table in list of dropped tables for db version56, a=chris

diff --git a/src/library/VersionFunctions.php b/src/library/VersionFunctions.php
index 1c2943ecb..bfa7f3997 100644
--- a/src/library/VersionFunctions.php
+++ b/src/library/VersionFunctions.php
@@ -1634,8 +1634,8 @@ function upgradeDatabaseVersion56(&$db)
         REMOTE_MESSAGE VARCHAR(" . C\MAX_DESCRIPTION_LEN . "),
         RESULT_STATE VARCHAR(" . C\NAME_LEN . "),
         RESPONSE VARCHAR(" . C\MAX_DESCRIPTION_LEN ."))");
-    foreach (["INTENT", "EXPRESSION", "ENTITY", "INTENT_EXPRESSION_ENTITY",
-        "BOT_TERM_FREQUENCY"] as $table) {
+    foreach (["BOT_TERM_FREQUENCY",  "ENTITY", "EXPRESSION", "INTENT",
+        "INTENT_EXPRESSION_ENTITY", "LEXICON"] as $table) {
         $db->execute("DROP TABLE $table");
     }
 }