[bug 1006951] Do not pre-select the mentees of a mentor in the email form.
Merge pull request #741 from akatsoulas/1006951

[bug 1006951] Do not pre-select the mentees of a mentor in the email form.
Add statsd counters for inactivity notifications.
[Fix bug 997275] Build event metrics management interface.

* Remove old metrics related_name.
* Add EventMetric and EventMetricOutcome models.
* Show EventMetric to base content.
* Fix /stats/ URL conflict with admin URL.
* Register new models to admin.
* Minor fixes in new models Meta.
* Replace old metrics with new metrics.
* Remove unused code from old metrics.
* Change templates to handle new metrics.
* Minor compatibility fixes between old and new metrics.
* Add factory for new metrics
Merge pull request #725 from johngian/997275-metrics-interface-dev

Build event metrics management interface.
Merge pull request #738 from johngian/add-stastsd-notifications

Add statsd counter for inactivity notifications.