Added support for custom oauth2 connections

[glena]

const options = { 
      theme: {
        authButtons: {
          "connectionName": {
            displayName: "...", 
            primaryColor: "...", 
            foregroundColor: "...", 
            icon: "url(...)"
          }
        }
      }
    };

const lock = new Auth0Lock(cid, domain, options);

[cristiandouce]

shouldn't this one be style?

[hzalaz]

yeah or color

[glena]

fixed 🐢