Moved some common styles into css classes

Makes them more maintainble for future. Also styles for class names can
be used to pull out similar elements in jQuery.
Fixed sections with no data being shown

Fixes https://github.com/shemul/fbCard/issues/1.
Gave "Founded" its own section, added code to complete section of AJAX
call that hides any sections that have no data in them.
Improved detection of parent to hide

This is for when there is no data in the section, now it is more
future-proof - assuming that back_section_header will house each
section.
Fixed runtime JS error

An error occured when trying to slice data.company.overview when
overview was undefined, eg: https://www.facebook.com/ironman, it now
checks before slicing and returns "None provided" if there is no data.
Adding checks for undefined location

The Iron Man page also does not have any location data so throws a
runtime JS error, fixed this up with some checks for undefined and
default values, if it is undefined then the address section is hidden.
Merge pull request #3 from BeigeBadger/master

Moved some common styles into css classes