Bug 7645 - System preferences editor save button obscured by language chooser

Bug 7645 - System preferences editor save button obscured by language chooser

This patch amends the preferences page's CSS file to add
bottom padding to the page container. This gives the bottom-
most submit button some breathing room.

Markup correction: Adding "row" and "col" attributes to
<textareas> to quiet validation errors. This doesn't
affect output at all (dimensions are specified in CSS).

To test, open the system preferences page to a tab like OPAC
which contains many preferences. At the bottom of the page
the last submit button should have about a line's worth of
white space below it.

Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>
Signed-off-by: Paul Poulain <paul.poulain@biblibre.com>