Fix exception when user is created w/o a group.

https://bugzilla.redhat.com/show_bug.cgi?id=1127093
Add test cases to reproduce the issue

where tag fields are not available in the service report.

https://bugzilla.redhat.com/show_bug.cgi?id=1127779
Add Service model to MiqExpression::TAG_CLASSES.

So the tags fields are listed in the service report.

https://bugzilla.redhat.com/show_bug.cgi?id=1127779
Add missing route and associated test

https://bugzilla.redhat.com/show_bug.cgi?id=1133051
https://bugzilla.redhat.com/show_bug.cgi?id=1133049