rename GroupPricing result class and test to Pricing.
change class name from GroupPricing to Pricing
change primary_column from group_pricing_id to pricing_id
rename GroupPricing test to Pricing.
rename GroupPricing class and relationships to Pricing.
Change Pricing has_many relationship from prices to pricings.
Remove table information from class and endable autotable via candy.
Merge pull request #117 from interchange/features/Pricing

Rename GroupPricing to Pricing