kobotoolbox: baseURL -> baseUrl

[josephjclark]

The kobotoolbox baseURL configuration should be renamed to baseUrl

Literally every other adaptor uses baseUrl. It's just this one that's different.

To preserve old credentials, I think it's worth supporting baseURL, but undocumented. Let's log a warning if baseURL is removed

Treat this as a breaking change.

So:

• Rename baseURL to baseURL in config and code
• In code, if baseUrl is not set and baseURL is provided, use baseURL but log a warning
• Major changeset