add gulp-imagemin

gulpfile.coffee

@@ -25,6 +25,7 @@ insert = require("gulp-insert")
 runSequence = require('run-sequence')
 lazypipe = require('lazypipe')
 rimraf = require('rimraf')
+imagemin = require('gulp-imagemin')
 
 mainSass = require("./main-sass").files
 
@@ -272,6 +273,7 @@ gulp.task "copy-fonts",  ->
 
 gulp.task "copy-images",  ->
     gulp.src("#{paths.app}/images/**/*")
+        .pipe(imagemin({progressive: true}))
         .pipe(gulp.dest("#{paths.dist}/images/"))
 
     gulp.src("#{paths.app}/plugins/**/images/*")

package.json

@@ -28,7 +28,8 @@
     "gulp-concat": "^2.1.7",
     "gulp-csslint": "^0.1.5",
     "gulp-flatten": "0.0.4",
-    "gulp-if": "0.0.5",
+    "gulp-if": "^1.2.5",
+    "gulp-imagemin": "^2.0.0",
     "gulp-insert": "^0.4.0",
     "gulp-intermediate": "^3.0.1",
     "gulp-jade": "^0.5.0",
@@ -52,7 +53,6 @@
     "readable-stream": "~1.0.31",
     "rimraf": "^2.2.8",
     "run-sequence": "^1.0.1",
-    "gulp-if": "^1.2.5",
     "through2": "~0.6.1"
   }
 }