Added a simple test for dbshard router.

The test sets a session variable and queries a union of this variable and a value in each of the databases.

server/test/MaxScale_test.cnf

@@ -57,6 +57,13 @@ user=maxuser
 passwd=maxpwd
 filters=Hint
 
+[DBShard Router]
+type=service
+router=dbshard
+servers=server1,server2,server3,server4
+user=maxuser
+passwd=maxpwd
+
 [RW Split Hint Router]
 type=service
 router=readwritesplit
@@ -109,6 +116,12 @@ service=RW Split Router
 protocol=MySQLClient
 port=4006
 
+[DBShard Listener]
+type=listener
+service=DBShard Router
+protocol=MySQLClient
+port=4010
+
 [RW Split Hint Listener]
 type=listener
 service=RW Split Hint Router