verifiy_ssl argument not passed to request in editissue method

Similiar problem as [#66](https://github.com/Itxaka/pyapi-gitlab/issues/66): the *verify_ssl* argument is not properly passed to the (post) request method. If GitLab instance uses an self-signed certificate, an error message is returned (even if verify_ssl is set to False in wrapper ctor):

```bash
...
ssl.SSLError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:548)
```

Tested with GitLab *6.6.5* (ad5e5b5) :)