Centered Tables + Fontawesome support

#### Centered Tables
As the main content of all slides is centered, I wanted to have also tables centered. Additionally, I was not that happy with the paddings inside the table. So this would do the trick ;-)

#### Fontawesome-Fixes
As Fontawesome uses the "i"-Tag, I had to remove reset of "i" (line 21 - this was because of fontawesome font sizes) as well as remove the tag for the italic definition (line 252). Now you can easily add Fontawesome to your slides by putting <link rel="stylesheet" href="css/font-awesome.css"> into the head of the html-file.