Static caption slot

[davestewart]

As per #144, this adds a new slot below the image which will allow a static caption to be displayed:

Caption below:

Caption overlay:

This is a fairly common use case, with minimal code.

I've bumped the minor version as it's a new feature (1.0.12 should have also been a minor bump because of the new changeDelay param).

[lukaszflorczak]

I've bumped the minor version as it's a new feature

Yes, it's true – my mistake