socket: allow upgrades if the socket is still in closing state

Fixes #284, courtesy of @3rd-Eden
Merge pull request #285 from lpinca/fix/gh-284

socket: allow upgrades if the socket is still in closing state (courtesy of @3rd-Eden)
Release 1.4.1
Add iframe onload handling to jsonp tests.

`onload` handling required for the `drain` event to fire. We need this
for some tests that look at socket closing.
Merge pull request #289 from rase-/fix/jsonp-test

Add iframe onload handling to jsonp tests.
polling: close the pending poll request when closing transport
socket: flush the write buffer before closing the socket (fixes #293)
Release 1.4.2
Merge pull request #294 from lpinca/fix/gh-293

socket: flush the write buffer before closing the socket (fixes #293)
Merge pull request #291 from lpinca/close/pending-request

polling: close the pending poll request when closing transport
package: bump `ws` to fix fd leaks
Release 1.4.3
Add cert tests.
Bump engine.io-client.
Additional SSL tests.
Bump engine.io-client.
Merge pull request #290 from rase-/add/cert-tests

Add ssl tests
Fix commit reference to client
Merge pull request #296 from rase-/fix/build

Fix commit reference to client