Successful connect() does not set 'closed' field to 'false'

[RaptDept]

1. Connect successfully
2. Wait until connection is closed (this.closed === true)
3. Call connect() again
4. Call some command, e.g. put()
5. Error('Connection is closed') is thrown from client.js

[mickhansen]

Hi @RaptDept,

That sounds highly odd, the libraries i use on top of this often call connect.
Could you open a PR with a failing test in https://github.com/burstable/node-beanstalkd-client/blob/master/test/integration/client.test.js?

[mickhansen]

Ah, thinking of it i don't think i reuse any instances of client after they close.