Bugfix in discovery plugins - ssh_proxmox, ssh_3par, ssh_ssg

* adding missing ip parameter in `DiscoveryWarning` usage in `ssh _proxmox` and detect a blank line in output in `_add_virtual_machine()`
* show notification when `ssh_ssg` authorization data not specifed in `settings.py`
* fix adding `share_id` field into history from `ssh_3par`
* http://ralph.allegrogroup.com/buildbot/builders/unittest-ralph-quamilek/builds/1951

* better detection `related_fields` in `HistoryDevice` field changes