Added base rewrite and tests for one method.

Need to test inherit still.
Added more tests for heir.inherit.
Added heir.mixin tests, need to write the function.
Added the mixin method source.
heir.createObject now uses the native method if there.
Tested the use of instanceof.
Add a more general purpose "merge" method. 

If we have a "merge" method, it fully duplicates the functionality presented in https://github.com/Wolfy87/Heir/pull/4, but in a much nicer way. 

I also added `heir.hasOwn`, as a shortcut for `Object.prototype.hasOwnProperty`. The "why"s for that are explained in the method's DocBlock.
Fix a little bit of layout
Styling tweaks for the merge pull request.
Tested heir.hasOwn.
Tested merge and fixed an error.

Merge was merging the entire source object into each destination value,
not the individual key values.
Added this.super and tests.
Now using a nicer UMD method.
Updated the example in the readme.
Readme issues link now uses the nice format.
Added mixin to the example.
Added some line breaks into the UMD section.
Readme super use now uses call.

Increases clarity as to how you actually use it.
Add an option to disable adding the super to the object
Added a test for the super flag.