Pretty soon we would like to move to XML/Angle Bracket style
components. As they are XML-y it means you can't use positional
parameters anymore (every 'argument' for the component requires it to
use an XML-like attribute).
This adds a `name=""` attribute to both block-slot and yield-slot
components so we can use attributes to specify the name. We prefer using
attributes from now on, whilst the positional parameter is still
available yet deprecated so we can move over at whatever speed fits.
We also did the same with the block params positional parameter.
As a final note this entire in repo addon is a fork of
`ember-block-slots`
The original version of ember-block-slots doesn't support ember 3 and it
seems like development has stalled on the original version.
This adds a modified version as an in-repo-addon that is compatible with
ember 3.
John Cowen