Update to make clear that none of the 3 dates were available 

Need to check with @janszumiec whether the date of the first choice is also pulled into the email
Updated status page to explain why visits may be rejected
Add requested time and alternatives to rejection email
Slot picker with 'alternative' slots
Update to SlotPicker 0.21.1
Update SlotPicker to 0.22.1

IE fix
Promotion transitions (animations)
Merge pull request #34 from ministryofjustice/leigh

Updated status page for rejected visits, updated 'visit rejected' email
Merge pull request #40 from ministryofjustice/alternative

Alternative
Update MoJ template to 0.16.1

Removes 'the' from 'Built by' in footer.
Upgraded logstasher to 0.6.1.
Added the pg gem.

[#78038926]
Added active_record configuration.

[#78038926]
Added a model to represent metrics for a single visit.

[#78038926]
Added the database_cleaner gem.

[#78038926]
MetricsLogger now uses VisitMetricsEntry.

[#78038926]
Added a migrator.

[#78038926]
Removed no longer used pieces, changed templates, adjusted CalculatedMetrics.
Removed references to redis from the app, as we're no longer using it for caching.

[#78038926]
Minor PR-related changes.

[Finishes #78038926]
Test fixes.