Remove Twitter?

[kelle]

@mwcraig : should we remove the role or change to X. or just mark as unfilled?

[mwcraig]

I would be inclined to remove the role but make sure to keep the account so that no one else can take the name. I'd also stop linking to it. No need to make a big deal out of it, just let it fade away....

[pllim]

Please see #634