more fanciness for blank options

[ajb]

• for regular <select>s, allow placeholder text to be different than blank text
• for .dropdown_selects, allow placeholder text to be different than blank text. also add .blank class to blank option in dropdown.

closes #153

[jrubenoff]

Cool. I added dashes to the blank options, so you can better visually differentiate it from a dropdown that's filled in:

LGTM

[ajb]

Can we do parens or an em-dash (—) instead?

Also note that the file you edited is just the configuration for the style guide itself. The blank option needs to be set in each host app, either on a per-app or a per-field basis.

[jrubenoff]

Yeah, I just want to add this example as a reference going forward.

Not sure how to properly add HTML-escaped entities (—) to that file.

[ajb]

OK, we'll use parens then ;)