Make provider status styles consistent with password strength

[iandunn]

Broken off of #141

...the iconography (check vs. X), the use of color and notices, and the indicators for whether something is complete or incomplete (in this case, steps in the stepper) could/should arguably share DNA with the same iconography and indication we use for password strength, if not now then at least at some point in the future.

Here are a couple of quick snaps from Francisco's work, which relies more on the high contrast which gray icons and text can give, compared to stoplight colors:

[iandunn]

I'm not sure if this should be in the MVP milestone or not, so I set it for Iteration 1 for now. Feel free to move it if anyone wants, though.