Parameter changes to ion defs
Changes to CSV preload files
Added new script to download CSV files
New REL file (more preload scenarios and special loading order)
Makes some changes to object definitions.

Adds new fields to parameter contexts for searching.

ParameterContextResource now has value_encoding, fill_value and unit_of_measure fields to aid in searching for
specific parameters.

Moves r2deploy changes to r2params.yml

Changes to pdefs

Updated CSV files

Updates to csv

CSV changes
Merge pull request #267 from lukecampbell/params

Params