[Fix bug 989292] Send email when member gets removed from group
[Fix bug 1076865] Add alternate email addresses in ExternalAccount.

* Add TYPE_EMAIL in ExternalAccount model.
* Exclude TYPE_EMAIL from external account formset.
* Exclude TYPE_EMAIL from accounts property.
* Implement various model properties as custom attributes.
Implement UserProfile privacy aware properties in __getattribute__ method.
[fix bug 1093322] Add Upper and Lower Sorbian in localized languages.
[fix bug 1098308] Add test coverage in mozillians.org .
[Fix bug 1101488] Add http[s]://*.mozilla.org URLs in CSP policies.
[Fix bug 1064486] add "Admin settings" to be translated