Ewsxmlreaderfix

[serious6]

ref. #337

I got the following exception when the subject of one email subject is : =?iso-8859-1?Q?=00?=
and empty appointments got the same error, I think it is also a solution to #262

microsoft.exchange.webservices.data.EWSHttpException: Connection not established
     at microsoft.exchange.webservices.data.HttpClientWebRequest.throwIfConnIsNull(Unknown Source)
     at microsoft.exchange.webservices.data.HttpClientWebRequest.getResponseHeaders(Unknown Source)
     at microsoft.exchange.webservices.data.ExchangeServiceBase.processHttpResponseHeaders(Unknown Source)
     at microsoft.exchange.webservices.data.SimpleServiceRequestBase.internalExecute(Unknown Source)
     at microsoft.exchange.webservices.data.MultiResponseServiceRequest.execute(Unknown Source)
     at microsoft.exchange.webservices.data.ExchangeService.findItems(Unknown Source)
     at microsoft.exchange.webservices.data.ExchangeService.findItems(Unknown Source)

@atamer

[azurecla]

Hi @serious6, I'm your friendly neighborhood Azure Pull Request Bot (You can call me AZPRBOT). Thanks for your contribution!
You've already signed the contribution license agreement. Thanks!
We will now validate the agreement and then real humans will evaluate your PR.

TTYL, AZPRBOT;