Squad

* core/admin:
* display "moderate notifications" in project listing
* filter ProjectStatus by project
* add several filters for the project listing
* settings: set `SERVER_EMAIL`

* ci:
* mark proper TestRun status on awkward LAVA failure
* frontend:
* display squad version in the base template
* several improvements to the UI to make browsing data more effective
* core:
* notitifications are now sent immeditately after there is enough data for
each build, instead of on pre-scheduled times.
* notifications can now be moderated by admins before being sent out to
users.

* core:
* update "last updated" data every time new results arrive for a given build
* notification: clearly identify tests that never passed as such
* ci:
* lava: report incomplete TestRun when TestJob is canceled
* frontend:
* fix group page to use correct status data (pass/fail counts, metric summary)

* core:
* Test names are now ordered alphabetically by default
* Site home page and project home page were fixed to display the correct build
status information (tests pass % and metric summary)
* notification: avoid spurious empty lines in plain text notification
* admin: allow filling in slug when creating Environment
* notification: group columns by environment in changes table
* notification: send a single email
* record project status at submission time instead of only when processing
notifications
* notification: add a per-project flag to control whethet to send a text/html
alternative representation together with plain text content
* ci:
* add job\_url to TestRun metadata if present
* ci/lava
* filter LAVA logs to include only the serial console output
* infrastructure
* settings: enable exception notifications by email
* frontend:
* fix resubmit JS code
* serve TestRun logs directly (i.e. allow viewing them in browser instead of
forcing a download)