Release v2.1.1 (#312)

FEATURES:
* Added the groups parameter to the resource, permitting users to use the jest docker ecryptfs dev claim in the token [#PR301](https://github.com/gambol99/keycloak-proxy/pull/301)
* Removed the authors file [#PR299](https://github.com/gambol99/keycloak-proxy/pull/299)

FIXES:
* Fixed the custom headers when upgrading to websockets [#PR311](https://github.com/gambol99/keycloak-proxy/pull/311)
* Fixed exception when upgrading to websockets [#PR303](https://github.com/gambol99/keycloak-proxy/pull/303)