Remove full stops from the end of primary text in dialogs

The GNOME HIG, 3.4.1 "Alert Text" states:

    ...  The primary text is punctuated in 'newspaper headline' style,
    that is, it has no terminating period, but it may have a terminating
    question mark.

http://developer.gnome.org/hig-book/3.0/windows-alert.html.en#alert-text