Moving the webkit bioid array to each yaml?

[j-ro]

Thoughts on moving the requires_webkit constant from https://github.com/EFForg/congress-forms/blob/69eff91202d10b40de6fb3fdc358a2f5b20481f2/config/constants.rb and putting it in each YAML file instead?

Makes more sense in some ways, and allows us to incorporate this constant with our git pulls from the contact congress repo, instead of having to restart everything when this changes.

Also, helpful for testing, so you understand why a yaml may not be working in phantomjs if you're testing that way.

[Hainish]

This relates to the discussion on whether the YAML files should be tied to a particular implementation, here: unitedstates/contact-congress#1402 (comment)