http request might return 503 if too many requests are sent at the same time

[edwardez]

api.bgm.tv will return 503 if too many requests are sent at the same time

artillery quick --count 100 -n 1 https://api.bgm.tv/subject/1

Report 
  Scenarios launched:  100
  Scenarios completed: 100
  Requests completed:  100
  RPS sent: 22.32
  Request latency:
    min: 197.1
    max: 2241.2
    median: 225
    p95: 2216.6
    p99: 2231
  Codes:
    200: 20
    503: 80

in order to bypass CORS, all requests are proxied through our own server
might be a problem in production (proxy pool/convert app into a ionic one/request bangumin to be added to the Access-Control-Allow-Origin list?)

[edwardez]

close in favor of #7