message: Updated Readme to work on default example.
  Could yield a better error message. Nonetheless, to lowercase seems to fix the issue. Much more testing is required.
diff: @@ -69,29 +69,29 @@ This package can be installed via npm or yarn.
  //Sample Private App Config
  {
  "UserAgent" : "Tester (PRIVATE) - Application for testing Xero",
  - "ConsumerKey": "AAAAAAAAAAAAAAAAAA",
  - "ConsumerSecret": "BBBBBBBBBBBBBBBBBBBB",
  - "PrivateKeyPath": "/some/path/to/privatekey.pem",
  - "RunscopeBucketId" : "xxxyyyzzzz"
  + "consumerKey": "AAAAAAAAAAAAAAAAAA",
  + "consumerSecret": "BBBBBBBBBBBBBBBBBBBB",
  + "privateKeyPath": "/some/path/to/privatekey.pem",
  + "runscopeBucketId" : "xxxyyyzzzz"
  }
  //Sample Public App Config
  {
  "UserAgent" : "Tester (PUBLIC) - Application for testing Xero",
  - "ConsumerKey": "AAAAAAAAAAAAAAAAAA",
  - "ConsumerSecret": "BBBBBBBBBBBBBBBBBBBB",
  - "AuthorizeCallbackUrl": 'https://www.mywebsite.com/xerocallback',
  - "RunscopeBucketId" : "xxxyyyzzzz"
  + "consumerKey": "AAAAAAAAAAAAAAAAAA",
  + "consumerSecret": "BBBBBBBBBBBBBBBBBBBB",
  + "authorizeCallbackUrl": 'https://www.mywebsite.com/xerocallback',
  + "runscopeBucketId" : "xxxyyyzzzz"
  }
  //Sample Partner App Config
  {
  "UserAgent" : "Tester (PARTNER) - Application for testing Xero",
  - "ConsumerKey": "AAAAAAAAAAAAAAAAAA",
  - "ConsumerSecret": "BBBBBBBBBBBBBBBBBBBB",
  - "AuthorizeCallbackUrl": 'https://www.mywebsite.com/xerocallback',
  - "PrivateKeyPath" : "/some/path/to/partner_privatekey.pem",
  - "RunscopeBucketId" : "xxxyyyzzzz"
  + "consumerKey": "AAAAAAAAAAAAAAAAAA",
  + "consumerSecret": "BBBBBBBBBBBBBBBBBBBB",
  + "authorizeCallbackUrl": 'https://www.mywebsite.com/xerocallback',
  + "privateKeyPath" : "/some/path/to/partner_privatekey.pem",
  + "runscopeBucketId" : "xxxyyyzzzz"
  }
  ```
  