Add docker support

docker-ledger/Ratpack.groovy

@@ -0,0 +1,16 @@
+@Grapes([
+        @Grab('io.ratpack:ratpack-groovy:1.5.4'),
+        @Grab('org.slf4j:slf4j-simple:1.7.25')
+])
+
+import com.devsoap.dbt.DBTModule
+
+import static ratpack.groovy.Groovy.ratpack
+
+ratpack {
+    bindings {
+        module (DBTModule) { config ->
+            config.executor.remoteUrl = System.properties.getProperty('dbt.executor.url')
+        }
+    }
+}