Style GtkProgressBar - SL #4249
Style GtkProgressBar - SL #4249

- add dark grey border
- use grey background fill for common progressbars
- use black background fill for progressbars in palettes or toolbars
- remove hardcoded values

Signed-off-by: Manuel Quiñones <6f5069c5b6be23302a13accec56587944be09079@laptop.org>
Acked-by: Simon Schampijer <088e16a1019277b15d58faf0541e11910eb756f6@laptop.org>

ceibal-tatu/sugar-artwork,sugarlabs/sugar-artwork,i5o/sugar-artwork,samdroid-apps/sugar-artwork,sugarlabs/sugar-artwork,tchx84/debian-pkg-sugar-artwork,tchx84/debian-pkg-sugar-artwork,i5o/sugar-artwork,i5o/sugar-artwork,godiard/sugar-artwork,samdroid-apps/sugar-artwork,tchx84/debian-pkg-sugar-artwork,sugarlabs/sugar-artwork,ceibal-tatu/sugar-artwork,ceibal-tatu/sugar-artwork,godiard/sugar-artwork,godiard/sugar-artwork,samdroid-apps/sugar-artwork