[1792] added a simple lettuce for the "inmemory w/ SQLite3 backend" scenario.

right now it does a simple check for loading and query response from the loaded
zone.  this is intended to be used for the inmemory-from-xfrin scenarios.

tests/lettuce/configurations/inmemory_over_sqlite3/secondary.conf

@@ -0,0 +1,24 @@
+{
+    "version": 2,
+    "Logging": {
+        "loggers": [ {
+            "debuglevel": 99,
+            "severity": "DEBUG",
+            "name": "auth"
+        } ]
+    },
+    "Auth": {
+        "datasources": [ {
+            "type": "memory",
+            "zones": [ {
+                "origin": "example.org",
+                "file": "data/example.org.sqlite3",
+	        "filetype": "sqlite3"
+            } ]
+	} ],
+        "listen_on": [ {
+            "port": 47806,
+            "address": "127.0.0.1"
+        } ]
+    }
+}

tests/lettuce/features/inmemory_over_sqlite3.feature

@@ -0,0 +1,9 @@
+Feature: In-memory zone using SQLite3 backend
+    This feature tests the authoritative server configured with an in-memory
+    data source that uses the SQLite3 data source as the backend, and tests
+    scenarios that update the zone via incoming zone transfers.
+
+    Scenario: Load and response
+        Given I have bind10 running with configuration inmemory_over_sqlite3/secondary.conf
+        A query for www.example.org should have rcode NOERROR
+        The SOA serial for example.org should be 1234