Add browser build + CDN link

[lmiller1990]

v-drag should be able to be used in an browser env from a cdn like this:

<script src="/some.cdn/v-drag"></script>

[yk-hirao]

How is "unpkg" ?
setting link is 'http://co.bsnws.net/article/233'

[lmiller1990]

sounds good. can you try and set it up? @yk-hirao