[fix] grunt action name

.travis.yml

 script:
   - ./manage.sh pep8_check
   - ./manage.sh styles
-  - ./manage.sh grunt
+  - ./manage.sh grunt_build
   - ./manage.sh py_test_coverage
   - ./manage.sh robot_tests
 after_success:

manage.sh

 	build_style themes/pix-art/less/style.less themes/pix-art/css/style.css
 }
 
-grunt() {
+grunt_build() {
 	grunt --gruntfile "$SEARX_DIR/static/themes/oscar/gruntfile.js"
 }