Removed white-background from ul.gallery; Updated commonPrint gallery styles

Removed white-background from ul.gallery; Updated commonPrint gallery styles

Since a while now proper margins and overflow prevent underlines and stuff from shining through other elements (such as tables, thumbs and galleries). Therefore there's no longer a need to force a white-background which caused ugly galleries on (parts of) pages with a non-white background (ie. a table.wikitable, or div.toccolours or  Commons' {{Information}} template)

The printstyles were outdated (stil targeted <table> instead of the new fluid galleries' <ul>). Updated now and white background removed there as well

* This commit fixes (bug 27458) Remove white background-color from ul.gallery
* r65923 introduced print-style for galleries (to make them look like galleries instead of tables)
* r77411 made galleries fluid and therewith changed the element from <table> to <ul>