Media processing panel layout improvements

[Aaron Williamson]

schendje and aaronw suggested some improvements to the panel's appearance:

• The introductory text ("You can track...") is probably unnecessary (at least as long as the content is self-descriptive)
• Failed and successful uploads can be combined into a single list ("Recent uploads") that distinguishes successful from failed uploads by color and/or other indicators
• Column headings should be left-aligned like column contents to improve readability
• The headings are not very visually distinct from the rest of the content -- indenting the tables a few em's to the right might help.