leniency for https

This should hopefully fix

```
javax.net.ssl.SSLException: hostname in certificate didn't match: <jenkins.akka.io> != <*.typesafe.com> OR <*.typesafe.com> OR <typesafe.com>
        at org.apache.http.conn.ssl.AbstractVerifier.verify(AbstractVerifier.java:228)
<snip>
        at dispatch.classic.Http.apply(Http.scala:21)
        at backend.PullRequestCommenter$$anonfun$receive$1.applyOrElse(PullRequestCommenter.scala:51)
```

seen in https://github.com/akka/akka/pull/1381