removed deprecated gulp-minify-css in favour of gulp-cssnano

gulpfile.js

@@ -12,7 +12,7 @@ var jshint       = require('gulp-jshint');
 var lazypipe     = require('lazypipe');
 var less         = require('gulp-less');
 var merge        = require('merge-stream');
-var minifyCss    = require('gulp-minify-css');
+var cssNano      = require('gulp-cssnano');
 var plumber      = require('gulp-plumber');
 var rev          = require('gulp-rev');
 var runSequence  = require('run-sequence');
@@ -104,7 +104,7 @@ var cssTasks = function(filename) {
         'opera 12'
       ]
     })
-    .pipe(minifyCss, {
+    .pipe(cssNano, {
       advanced: false,
       rebase: false
     })

package.json

@@ -34,12 +34,12 @@
     "gulp-autoprefixer": "^2.3.1",
     "gulp-changed": "^1.3.0",
     "gulp-concat": "^2.6.0",
+    "gulp-cssnano": "^2.1.0",
     "gulp-flatten": "0.1.1",
     "gulp-if": "^1.2.5",
     "gulp-imagemin": "^2.3.0",
     "gulp-jshint": "^1.11.2",
     "gulp-less": "^3.0.3",
-    "gulp-minify-css": "^1.2.0",
     "gulp-plumber": "^1.0.1",
     "gulp-rename": "^1.2.2",
     "gulp-rev": "^6.0.0",