Replace css of fork-awesome with its scss version (#592)

* Replace css of fork-awesome with its scss version

* Delete the CSS version of fork-awesome

assets/scss/fork-awesome/_core.scss

@@ -0,0 +1,12 @@
+// Base Class Definition
+// -------------------------
+
+.#{$fa-css-prefix} {
+  display: inline-block;
+  font: normal normal normal #{$fa-font-size-base}/#{$fa-line-height-base} #{$fa-font-family}; // shortening font declaration
+  font-size: inherit; // can't have font-size inherit on line above, so need to override
+  text-rendering: auto; // optimizelegibility throws things off #1094
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+
+}