I moved bower dependencies in my Ionic app from `./www/lib` to `./bower_modules` in order to slim down the resulting "www" package. Here are the gulp settings/tasks I use to compile/concatenate everything into `./www/js/libs.js`

gulpfile.js

var paths = {
  // Manually specify the bower resources we actually need.
  // This way our index simply has: <script src="js/libs.js"></script>
  bower: {
    scripts: [
      "./bower_modules/ionic/js/ionic.bundle.js",
      "./bower_modules/angular-resource/angular-resource.js",
    ],
    fonts: [
      "./bower_modules/ionic/fonts/**.*",
    ]
  },
};

// Bundles the bower scripts we're using into www/js/libs.js
gulp.task('bower-scripts', function(done) {
  gulp.src(paths.bower.scripts)
   .pipe(concat('libs.js'))
   .pipe(uglify({mangle: false}))
   .pipe(gulp.dest('./www/js'))
   .on('end', done);
});

// Copies fonts from Bower we're using into www/fonts/
gulp.task('bower-fonts', function(done) {
  gulp.src(paths.bower.fonts)
    .pipe(gulp.dest('./www/fonts'))
    .on('end', done);
});