Configtool About tab update

Updated the layout of the "About" tab to be more similar to that of the newly changed "Recording" tab.

Windows:
![about tab screenshot](https://cloud.githubusercontent.com/assets/5759678/4452270/38c14652-4844-11e4-8349-305fe83ce5a3.jpg)

Linux:
![about tab screenshot](https://cloud.githubusercontent.com/assets/5759678/4452278/56d02d48-4844-11e4-9784-d5827105f247.png)

@dideler Does replacing self.logoPixmap here with QPixmap(_fromUtf8(":/freeseer/logo.png")) make the icon appear?
It's gotta be either the stylesheet or the scaling.

It could be that my math for the margins only works for my resolution.