Release 0.8.0

This is another maintenance release to merge a number of community pull requests. This merges #165 #167 #170 #171 #172 #173. Thanks to everyone for their contributions.

#170 in particular could break some tests if you use the test addon. So make sure to check that out if you are having issues with tests after upgrading.

In general this repo is is maintenance mode as Ember Octane has changed how you can implement drag and drop significantly with modifiers. See -> https://dev.to/dgavey/simple-drag-and-drop-in-ember-octane-466i