slight makefile refactoring

Makefile

@@ -7,14 +7,16 @@ port=5432
 database=postgres
 verbose=false
 
+params := -u $(user) --password $(password) -p $(port) -d $(database) -h $(host) --verbose $(verbose)
+
 test-connection:
-	@node script/test-connection.js -u $(user) --password $(password) -p $(port) -d $(database) -h $(host) --verbose $(verbose)
+	@node script/test-connection.js $(params)
 
 test-unit:
-	@find test/unit -name "*-tests.js" | xargs -n 1 -I file node file --verbose $(verbose)
+	@find test/unit -name "*-tests.js" | xargs -n 1 -I file node file $(params)
 
 test-integration: test-connection
-	@find test/integration -name "*-tests.js" | xargs -n 1 -I file node file -u $(user) --password $(password) -p $(port) -d $(database) -h $(host) --verbose $(verbose)
+	@find test/integration -name "*-tests.js" | xargs -n 1 -I file node file $(params)
 
 test-all: test-unit test-integration
 test: test-unit