improve style for accordion contents

• if language_tabs are withing the accordion content, then remove line between heading and tabs
  by adding a new class the sets the top margin to -1px
make column display type numeric for aligning

• enlarge status_section part so the updated infos are displayed in one line
fix admin-menu select background image

• improve and move drop-down icon so it's hidden behind Firefox generic drop-down image
• and still is looking good in Safari and Chrome