Return a message when a 429 http response is received (#115)

This adds a case for handling 429 responses from Simperium, which has an empty response body, and adds a response text which can then be used to handle this error specifically.

Update release notes

Fix typo in release notes

v1.1.0

Refactored several internal components in order to work more seamlessly
between Node and browser environments. There should be no API or behavioral
changes in this release.

When using bundlers like `webpack` this no longer relies on the provided
polyfills for the Node libraries that are missing on the web platform.

v1.0.4

 - Update diff-match-patch fix for surrogate pair issue

Merge pull request #95 from Simperium/update/bump-version

Bump versionn to 1.0.3

v1.0.2 Release

 - Fix diff-match-patch problem encoding consecutive surrogate pairs [#91]

v1.0.1 Release

 - When connecting, disconnect socket if it's already open [#90]

v1.0.0 Release

 - Stop re-sending changes marked as duplicates by the server [#73, #74]
 - Allow `async` and `await` in tests [#81]
 - Update API adding `onBeforeNetworkChange` and fix syncing issues when
   receiving updates while also waiting for confirmation on local
   changes [#82, #83, #78, #61]
 - Dependency updates

0.3.2