jdbc: support for DatabaseMetaData.getSQLStateType

Now we use SQLSTATE codes in most of the exceptional cases. To be
consistent with it we need to return an appropriate value from the
database metadata.

This commit changes the constant that says the driver works with
SQLSTATE codes rather than XOpen ones.

Closes #119

Author: nicktorwald

Diff for: src/main/java/org/tarantool/jdbc/SQLDatabaseMetadata.java

@@ -1037,7 +1037,7 @@ public int getJDBCMinorVersion() throws SQLException {
 
     @Override
     public int getSQLStateType() throws SQLException {
-        return 0;
+        return DatabaseMetaData.sqlStateSQL;
     }
 
     @Override

Diff for: src/test/java/org/tarantool/jdbc/JdbcDatabaseMetaDataIT.java

@@ -390,4 +390,9 @@ public void testDeleteDetectionSupport() throws SQLException {
         }
     }
 
+    @Test
+    public void testSqlStateType() throws SQLException {
+        assertEquals(DatabaseMetaData.sqlStateSQL, meta.getSQLStateType());
+    }
+
 }