Separate out logic in initialisation code to help in separating native vs non-native code paths when supporting document.registerElement.
Implement native custom element support.
Remove unnecessary registry methods.
Ensure we test all types compatible with tag bindigs.
Update doco to reflect changes. Remove stuff about differences to polymer and xtags. Seems kind of petty and by reading the readme of each project you should have a general idea anyways.
Merge pull request #112 from skatejs/GH-46

Use document.registerElement if compatible and available