Comment 2 for bug 968974

Specification updated. <https://wiki.ubuntu.com/SoftwareCenter?action=diff&rev2=623&rev1=622> "If the item is not installed nor queued for installation, the price of the item (e.g. 'Free') at the leading end, and a button at the trailing end: 'Buy…' if installation requires sign-in and payment, 'Install…' if it requires sign-in only, or 'Install' if it requires neither."

I don't think varying "Install" to "Install…" is worth breaking string freeze for Pangolin.