Update paper size names

Update list of standardized paper size names from
PWG Media Standardized Names 2.0 (MSN2) and from
CUPS' cups/pwg-media.c.

https://bugzilla.gnome.org/show_bug.cgi?id=725441
Create paper size from IPP media name

Add function gtk_paper_size_new_from_ipp() which looks for
given name in standard paper size names list and create appropriate
GtkPaperSize.

https://bugzilla.gnome.org/show_bug.cgi?id=725441
Remove dead code from CUPS backend

https://bugzilla.gnome.org/show_bug.cgi?id=725441
Get paper sizes from IPP query

Query printer via IPP for paper sizes if there is no
or empty PPD file.
Parse "media-supported" and "media-size-supported" attributes for list
of paper sizes. Parse "media-default" and "media-col-default" attributes
for default settings.

https://bugzilla.gnome.org/show_bug.cgi?id=725441
Add top/bottom style classes to scroll arrows
Updated Italian translation
Adwaita: style menu overflow button

See bug https://bugzilla.gnome.org/show_bug.cgi?id=738158
Adwaita: dim menu overflow button border color