Cursor integration

[abbashus]

Issue: #74

Description of changes:
This change is a part of the cursor support for JDBC driver to use new paginated response.

Usage:

• The default value of fetchSize is 0 - meaning user will get non-paginated response as supported by Opendistro SQL plugin
• The fetchSize can be provided in multiple ways:
  • Via connection string

      String url = "jdbc:elasticsearch://localhost:9200?";
      ...
      Connection con = DriverManager.getConnection(url);

• By passing Properties object

Example 1:

        Properties properties = new Properties();
        properties.setProperty("fetchSize", "300");
        Connection con = DriverManager.getConnection(url, properties );

Example 2:

        InputStream input = new FileInputStream("path/to/config.properties")
        Properties properties = new Properties();
        properties.load(input);
        Connection con = DriverManager.getConnection(url, properties);

• By setting directly on Statement as JDBC 4.1 spec (13.5)

        Connection con = DriverManager.getConnection(url );
        Statement st = con.createStatement();
        st.setFetchSize(500);

When fetchSize is set in mutliple places, the final fetchSize value used is picked based on the following order of precedence:

Statement.setFetchSize() > Properties > Connection String

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[davidcui1225]

+1 to Chen's comment about adding Javadoc & UTs

[chloe-zh]

LGTM, thanks!