Fix deleting connection.sid from pool before disconnecting it

[jpreynat]

Calling client.clientEnd() causes the following error:

TypeError: Cannot read property 'disconnect' of undefined
      at node_modules/thunk-disque/lib/client.js:88:17
      at Object.exports.each (node_modules/thunk-disque/lib/tool.js:39:59)
      at DisqueClient.clientEnd (node_modules/thunk-disque/lib/client.js:87:10)
      ...

Deleting the connection's sid from disqueState.pool in lib/connection:

  disconnect () {
    ...
    let disqueState = this.disque._disqueState
    delete disqueState.pool[this.id]
    delete disqueState.pool[this.sid] // faulty line

causes the each function to crash when reaching the actual connection's sid in lib/client:

    tool.each(disqueState.pool, (connection, key) => {
      connection.disconnect()
      delete disqueState.pool[key]
    })

Can you please take this PR into account for a 0.5.1 release ?

Thanks in advance.

[zensh]

Thank you for your PR. I fixed it with another way 8c76d82#diff-50cfa59973c04321b5da0c6da0fdf4feR92

v0.5.1 released.

[zensh]

It need more tests, I will work it in this days

[jpreynat]

No problem, you know best how to fix this.
Thanks for upgrading it so quickly!