Test fix: force JSON format for tests (#203)

This commit fixes the integration tests past switching to CBOR by
default for the REST body format: the integration tests make use of the
(textual) JSON format, which needs to be enabled in the connection
string used by the simulated connection.

(cherry picked from commit 139d8be)

Author: bpintea

test/connected_dbc.h

@@ -100,7 +100,7 @@ extern "C" {
 }"
 
 /* minimal, valid connection string */
-#define CONNECT_STRING L"Driver=ElasticODBC"
+#define CONNECT_STRING L"Driver=ElasticODBC;Packing=JSON;"
 
 class ConnectedDBC {
 	protected: