Add options to cache connection parameters

[123andy]

For refreshing the API link, it would be nice to be able to 'save' the API token and parameters.

• For example, if you want to include DAG, it should remember for that connection that the DAG is set to yes.
• for the API token, it would be nice to offer a save option. I left Tableau open for a day and when I tried to refresh the data source nothing happened (no errors, etc) and I was confused until I figured out that to refresh I had to go and re-enter the API token.
• Might be nice to be able to custom-name the linked table as it appears in Tableau as well so you could join multiple queries all together and have them logically named

[lsgs]

Good suggestions @123andy. I wonder if Tableau's browser would accept a cookie to remember some of the entered values? Specifying a data source name should be possible too as it is one of the properties you can set for the connector object.

Being honest, I don't think I can get on to enhancements for this module any time soon. Very happy to review pull requests though if you have someone that wants to have a go.