Support for Other inputs types besides Text

The Problem: Co-Authors-Plus Guest-Authors Profiles are very limited. If you want to expand on a existing Group ("Constact Fields") You can only use Text input types.

The Solution: A field item called Input that declares the field's type. This would be assumed by default to be text, and the existing, "hidden", "email" and "website" fields would be assigned the standard "hidden", "email" and "url" input types. 

In addition, for someone who may not want to website field to be forced to a real URL, a filter would be applied to each field's input to allow it to be override, without pulling all fields via "coauthors_guest_author_fields" filter.

The new filter would look something like this `$pm_key_input`. So to change Website back to text would be `apply_filter('cap_website_input', 'myfunction_that_returns_text');`

Does not yet support:
Select
MultiSelect
Radio (Easily)

Adds Support for:
Checkbox
Url
Email
Number/date fields