ORCID validation and URL stripping, got started on JavaScript

Hi, from taking at look at issue tracker here and the comments on http://pigsonthewing.org.uk/orcid-plugin-for-wordpress/, and from my own informal testing, I'm submitting this PR which should address the following issues:
1. Removed tabindex attributes, which fixed a problem with tabbing over the form fields,
2. Accounted for the possibility of the user adding the URL to their ORCID (instead of the ORCID number itself)
3. Added some very simple validation at both the server and JavaScript level. Someone with better Regex skills than me should maybe rewrite the actual regular expressions. The JS validation occurs both on the blog page (for comments) and the user/admin page.
Great job, the codebase is awesome, very easy to follow.
Casey