Update color of dashed lines

[arouinfar]

For phetsims/qa#221

In GFL(B), the color of the dashed lines was meant to match up with the masses. In CL, charges can be red or blue, which can lead to this somewhat odd-looking situation.

We could either

1. Make both lines gray. rgb(180, 180, 180) would work nicely.

2. Make the line color adaptive like the Charge slider thumbs: blue when negative, red when positive, gray when zero.

Option (2) would look a bit nicer, but option (1) seems quicker/easier. If option (2) is a quick(ish) and non-invasive change (the next rc could still be a spot check), then I'd like to pursue it @mbarlow12. Otherwise, let's go with option (1).

[mbarlow12]

@arouinfar I was able to have the color update along with the charge value. The colors themselves are a little muted compared to the slider thumb, but that can easily be changed if desired.

[arouinfar]

That's great @mbarlow12. I pulled all, but I'm not seeing any color changes. Did you commit the changes to master?

[mbarlow12]

No I didn't. They're made in 1.0 branch currently. I'll be sure to pull them ASAP.

[mbarlow12]

@arouinfar I just merged the branches into master.

[arouinfar]

Looks awesome @mbarlow12! Thanks.

[KatieWoe]

1.0.0-rc.6 this looks good.