admin: Add message for excluded users in details

Fix apyrgio/synnefo#269
admin: (Un)Drain only public networks

Fix apyrgio/synnefo#276
admin: Highlight reports and charts/stats

When a user is in a charts/stats category, then the report tab and the
stats/charts tab will become active.
admin: Add corresponding VM in IP info

Show in summary and details the VM that an IP is attached to.
Merge branch 'feature-admin-minor-fixes' into feature-admin