message: bumped to v2.2.0 in readme
diff: @@ -196,6 +196,8 @@ npm test
  ## Release Change Log
  +* 2.2.0
  + - Merged [PR#46](https://github.com/XeroAPI/xero-node/pull/46) - Merge PR#45 and provide library level support for boolean values (formerly this required string conversion).
  * 2.1.8
  - Merged [PR#44](https://github.com/XeroAPI/xero-node/pull/44) - Merge PR#43 and expose more contact fields (fix for issue #40).
  * 2.1.7
  