Added media queries for larger displays

Moved secondary content into a second column at displays over 40em, then a larger
column and 50em and 60em
Removed additional padding around the search form
Reduced the secondary content widget padding and margins
Changed footer links to light grey with a red underline
Changed post nav links to include the font awesome chevron instead of the standard
« or »
Changed the post meta font awesome items and post nav chevron colour on to #a00
Increased excerpt length to 120 from 100