Fixes for creating contracts

[d10sfan]

Fixes for the following issues related to creating contracts:

• Fix ListItemsInStation signature to allow for listing the items in station when creating a contract
• Add ListStations implementation that client was having issues with
• Add implementations for CreateContract, as parameters given differ depending on if it's a private contract versus public for example

This seems to be working well, as with the changes, I was able to create contacts with various settings (with and without descriptions, private vs public.

Not sure if there's a better way to handle the different arguments, as this needed lots of unique functions to catch the various ways that contracts are sent by the client.

[jdhirst]

Looks great, thank you!

[d10sfan]

Thanks!