add @each control directive & other small edits

Thanks for accepting my first request.  I hope you like this one too.

This request is quite a bit more in depth than my previous one, though I think this will help in maintaining the Sass file and adding / subtracting social classes in the future.

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Condense all individual social classes into two @each sass control directives that pull from the Sass variable list, $social-list.

To add new social classes, the name of the class comes first in the list, followed by the $rrssb-NAME.

The control directives take care of all the rest of repetitive rule declarations.


//  other edits in this PR

from li {} selector:

remove display: block; because <li>'s are already display blocks, and the float:left also makes the element a display block.

remove duplicate height: 100%;

remove duplicate .googleplus .style1, .style2, .style3.  these weren't any different than the first declaration in the cascade.