12677 slideshow split content

https://redmine.previousnext.com.au/issues/12677

With the new version of Features (beta-2.6), Fields are now separated into "base" and "instance". I ran into an issue where the Slideshow Feature was always showing as overridden even after reverting and clearing cache. The workaround to this issue is that I had to manually remove the *.features.field.inc and *.features.content.inc in order for it to properly update the Feature so that it no longer appeared overridden.

Once I fixed that I issue I could separate the content items into their own Feature.

To test:

* Reinstall aGov with default content
* Ensure that Slideshow appears with default slides after installation
* Disable default content
* Ensure that Slideshow is still present. Note - The slideshow does not appear if there is no content to display, so once you disable default content you need to add and publish a Slide node for it to appear in the Slideshow.