Add CodeSponsor.io badge

[coderberry]

CodeSponsor.io is a platform that connects sponsorship to open-source projects. Projects earn money from sponsors and this badge would indicate the amount earned per project.

The API to be hit is a simple GET request to
https://app.codesponsor.io/shields/[token]/[username]/[repo_name]

For example: https://app.codesponsor.io/shield/YOURTOKEN/hopsoft/bg

Example Results:

{
  "distribution_cents": 13625,
  "ts": 1505088625
}

[rstacruz]

neat, how do you get your token? :D