init app : API
update settings.py : add API to INSTALLED_APPS
update routing : /api
update settings.py : add rest_framework
add Link Serializer
update API app structure
update url/view : /api/links
fix error : shorten field is not required
Merge branch 'feature/basic-api' into develop

* feature/basic-api:
  fix error : shorten field is not required
  update url/view : /api/links
  update API app structure
  add Link Serializer
  update settings.py : add rest_framework
  update routing : /api
  update settings.py : add API to INSTALLED_APPS
  init app : API
add feature redirect : using RedirectView