Don't run get_resolve_time tests on SQLite

SQLite doesn't do aggregate functions on datetime fields:
https://docs.djangoproject.com/en/1.7/ref/models/querysets/#aggregation-functions
Add notification to assignee on reassign (DMT #96377)
Merge pull request #136 from nikolas/fix-reassign-bug

Add notification to assignee on reassign (DMT #96377)
fix merge conflict
Merge branch 'nikolas-fix-get-resolve-time-tests'