games-roguelike/cataclysm-dda: drop package mask

Cataclysm: DDA now has empty KEYWORDS rather than a package mask, as
recommended by Gentoo developers for live sources.
app-vim/powerline-python: update header
*: "sed -ie" -> "sed -i -e"

Such a newb mistake. *sigh*
app-{misc,vim}/powerline*: Nikolai's pull request

To (hopefully!) simplify life, I've manually merged the majority of Nikolai's
most recent pull request (#13).
app-{misc,vim}/powerline-status: powerline 1.0

Given the official renaming of Powerline to "powerline-status" with the 1.0
release, we've elected to rename all ebuilds accordingly while temporarily
retaining the prior ebuilds for backwards compatibility. The latter will be
removed at some future date, likely early in 2015.