Update html5shiv.js

Hi, :smile:

 I updated
* **html5shiv.js** in `assets/js`. I deleted the empty space. Now it looks like the other js files.
* **footer.htmk** in `_includes`. I add a dot.
* **.gitignore** in `_includes/vendor`. I add a gap.

Yours,
[**Suriyaa Kudo**](https://github.com/SuriyaaKudoIsc) :octocat: