[CHANGE] Attach uglify log errors to console.error

UglifyJS in the scripts task isn't catching errors.

```
stream.js:94
      throw er; // Unhandled stream error in pipe.
            ^
Error
    at new JS_Parse_Error (/home/i4k/projects/neoway/layer-manager/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:189:18)
```

For now:

```
{ [Error: /home/i4k/projects/neoway/layer-manager/build/js/layer-manager.js: Unexpected token name «fa», expected punc «,»]
  message: '/home/i4k/projects/neoway/layer-manager/build/js/layer-manager.js: Unexpected token name «fa», expected punc «,»',
  fileName: '/home/i4k/projects/neoway/layer-manager/build/js/layer-manager.js',
  lineNumber: 174,
  stack: 'Error\n    at new JS_Parse_Error (/home/i4k/projects/neoway/layer-manager/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:189:18)\n    at js_error (/home/i4k/projects/neoway/layer-manager/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:197:11)\n    at croak (/home/i4k/projects/neoway/layer-manager/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:656:9)\n    at token_error (/home/i4k/projects/neoway/layer-manager/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:664:9)\n    at expect_token (/home/i4k/projects/neoway/layer-manager/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:677:9)\n    at expect (/home/i4k/projects/neoway/layer-manager/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:680:36)\n    at /home/i4k/projects/neoway/layer-manager/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:1195:44\n    at /home/i4k/projects/neoway/layer-manager/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:703:24\n    at expr_atom (/home/i4k/projects/neoway/layer-manager/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:1152:35)\n    at maybe_unary (/home/i4k/projects/neoway/layer-manager/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:1327:19)',
  showStack: false,
  showProperties: true,
  plugin: 'gulp-uglify' }
```

We can use gulp-util too.

Thanks!