Replace API Keys with Personal Access Tokens

[nikunjve]

Intercom is replacing API keys with "Personal Access Tokens". Old requests will fail with effect from January 2017. Read more about here: https://developers.intercom.io/docs/personal-access-tokens

This module needs to be updated to handle this change.

[tarunc]

I haven't tried it but from Intercom's docs, it seems that passing in a personalAccessToken instead of an appId should just work (without passing in an apiKey) since both are accepted as http auth username parameters.

Thus, please try passing in a personalAccessToken as such

var options = {
  personalAccessToken: "your_access_token"
};

var intercom = new Intercom(options);
// OR can also be written as:
var intercom = new Intercom("your_access_token");

[jamesramsay]

Unfortunately this doesn't work because there is validation that checks for the existence of apiKey: https://github.com/tarunc/intercom.io/blob/master/lib/intercom.io.js#L42

If that's all that's needed to fix the issue I'll open a pull request.