Add optional social sharing buttons

- Social share buttons appear at the end of every post and page unless you add share: false to their YAML Front Matter
- Fixes #42

_sass/page.scss

@@ -561,6 +561,58 @@ $button-size: 1.5rem;
 	}
 }
 
+/* Social sharing links */
+/* Social media brand buttons */
+.social-share {
+  margin-bottom: 0px + $doc-line-height;
+  margin-bottom: 0rem + ($doc-line-height / $doc-font-size);
+  ul, li {
+  	margin: 0;
+  	padding: 0;
+  	list-style: none;
+  }
+  li {
+  	display: inline-block;
+  }
+  $social: 
+  (facebook, $facebook-color),
+  (flickr, $flickr-color),
+  (foursquare, $foursquare-color),
+  (google-plus, $google-plus-color),
+  (instagram, $instagram-color),
+  (linkedin, $linkedin-color),
+  (pinterest, $pinterest-color),
+  (rss, $rss-color),
+  (tumblr, $tumblr-color),
+  (twitter, $twitter-color),
+  (vimeo, $vimeo-color),
+  (youtube, $youtube-color);
+  @each $socialnetwork, $color in $social {
+    .#{$socialnetwork} {
+      background: $color;
+    }    
+  }
+  a {
+	  padding: 8px 20px;
+	  text-decoration: none !important;
+	  text-transform: uppercase;
+	  @include font-rem(14);
+	  font-family: $heading-font;
+	  font-weight: 700;
+	  color: $white;
+	  opacity: 0.8;
+	  &:hover {
+	    opacity: 1;
+	  }
+	}
+	h4 {
+		@include font-rem(14);
+		margin-bottom: 10px;
+		text-transform: uppercase;
+	}
+}
+
+
 /* Footer wrapper */
 .footer-wrap {
 	@include container;
@@ -611,7 +663,6 @@ $button-size: 1.5rem;
 		@include suffix(12,3.5);
 	}
 	h4 {
-		
 		text-transform: uppercase;
 		margin-bottom: 0;
 	}

_sass/variables.scss

@@ -37,6 +37,20 @@ $warning			: #dd8338;
 $danger				: #C64537;
 $info				  : #308cbc;
 
+/* brands */
+$facebook-color     : #3b5998;
+$flickr-color       : #ff0084;
+$foursquare-color   : #0cbadf;
+$google-plus-color  : #dd4b39;
+$instagram-color    : #4e433c;
+$linkedin-color     : #4875b4;
+$pinterest-color    : #cb2027;
+$rss-color          : #fa9b39;
+$tumblr-color       : #2c4762;
+$twitter-color      : #55acee;
+$vimeo-color        : #1ab7ea;
+$youtube-color      : #ff3333;
+
 /* links */
 $linkcolor 		    : #343434;
 $link-color       : $linkcolor;