Add "device_name" parameter to support juniper and Cisco devices

[KenzK]

From ncclient pypi page:
"As of 0.4.1 ncclient integrates Juniper’s and Cisco’s forks, lots of new concepts have been introduced that ease management of Juniper and Cisco devices respectively. The biggest change is the introduction of device handlers in connection paramms. For example to invoke Juniper’s functions annd params one has to re-write the above with device_params={‘name’:’junos’}""

Would be good if the support is added.

[vkosuri]

Thanks for update @KenzK , could you please create PR?