Fixed send_error and handshake docs
Bumped version to 1.2.1.1-beta
Merge branch 'release/1.2.1.1-beta' into develop
[JSONP] Fixed issue parsing double-escaped newlines

(https://github.com/Automattic/engine.io/commit/de0b4a9d4a88d4fa8a47bf0bf49b29d24678b523)
Bumped version to 1.3.1-beta
Merge branch 'release/1.3.1-beta' into develop