Provide a way to implement CSLB

[hexoul]

Motivation

• Sometimes there is a need to distribute traffics on client side like round-robin or weighted load balancing.
• At least, making endpoint of Dogma a list would be a good first step.
  • AS-IS: Dogma("https://dogma.yourdomain.com", "token")
  • TO-BE: Dogma(["http://10.0.0.1", "http://10.0.0.2", "http://10.0.0.3"], "token")