feat(icon): woff2 font format, smaller font files

gulpfile.js

@@ -340,7 +340,7 @@ gulp.task('sass', function() {
 });
 
 gulp.task('fonts', function() {
-  return gulp.src(['ionic/**/*.ttf', 'ionic/**/*.woff'])
+  return gulp.src(['ionic/**/*.ttf', 'ionic/**/*.woff', 'ionic/**/*.woff2'])
     .pipe(gulp.dest('dist'))
     .pipe(gulp.dest('dist/bundles'));
 });

ionic/fonts/ionicons.scss

@@ -10,7 +10,8 @@ $ionicons-version: "3.0.0" !default;
 
 @font-face {
  font-family: "Ionicons";
- src: url("#{$ionicons-font-path}/ionicons.woff?v=#{$ionicons-version}") format("woff"),
+ src: url("#{$ionicons-font-path}/ionicons.woff2?v=#{$ionicons-version}") format("woff2"),
+      url("#{$ionicons-font-path}/ionicons.woff?v=#{$ionicons-version}") format("woff"),
       url("#{$ionicons-font-path}/ionicons.ttf?v=#{$ionicons-version}") format("truetype");
  font-weight: normal;
  font-style: normal;