Add owner checks to report_count queries

[mattmundell]

What:

Only use the current user's cached report_counts when getting a report's severity.

Needed because overrides may change the severity across users. Without
overrides the max severity of a report is the same for all users.

Why:

GET_TASKS was returning wrong info.

How did you test it:

1. create 2 users
2. share a report that has no high results between the users
3. override one result to high as user1
4. look at the report with both users with overrides applied, to get the counts cached
5. as user2 run '<get_tasks filter="apply_overrides=1 severity=10 min_qod=70"/>' This will return the shared task, even though the severity is not overridden to 10 for this user.
6. as user2 run '<get_tasks filter="apply_overrides=1 high>0 min_qod=70"/>' Similarly this will return the shared task.

Same result with Dynamic Severity on and off.

Checklist:

• Tests
• CHANGELOG Entry