Add "merit:archive" Rake task

Exports data about a Merit Order run, including load, price, and
producer data.

Closes quintel/merit#117
Merit Order dump includes the calculation time
merit:archive task can now export using Presets
Changes to work with the latest Merit gem

Merit updated to quintel/merit@c9e66af
Atlas updated to quintel/atlas@f6bb51a

Load profiles are no longer auto-loaded by the Merit gem, but instead
are expected to be fully-formed Merit::Curve objects. The Atlas dataset
will take care of loading the correct curve.
Cache load profiles
Add inputs:dump Rake task

Dumps the min, max, and starting values for all inputs for each dataset.
This can be used with Atlas' "preset:fix" task to adjust the user values
of presets to ensure that share groups sum to 100.
"bulk_update" now uses Atlas' ScenarioReconciler

... user values will be removed when an input has been deleted, values
altered if the min/max of the input has changed, and share groups
re-balanced as required.

Closes quintel/etsource#524.
Update Atlas to quintel/atlas@e5ddbe0

This version of Atlas will load the newer CSV load profiles in ETSource.