Changes to the data model to reconcile with caac-map

[dmtroyer]

• Added after_this and before_this attributes to Opportunity which are references to other opportunities.
• Added badge_class_id to Opportunity, which should reference a badge class id url ala the open badges spec.
• Added resource_type and resource_sub_type models and subsequent attributes to Opportunity and OpportunityInstance which default to opportunity's if the instance doesn't have one.
• Removed hardcoded type on Opportunity and OpportunityInstance
• Updated seed data

@MatthewVita @timothyfcook yinz want to take a look at this? should reconcile differences we found with caac-map in #163.

@whit537 turns out nothing really seems to need to change in caac-map itself, I updated the google spreadsheet, maybe regenerate output/topics.json. I tried but failed, having trouble with python 3.5 on my vagrant.

[MatthewVita]

This all looks great to me! Merging to master.

[MatthewVita]

My only tiny comment would be to add a comment above the following lines

cityasacampus/app/models/opportunity_instance.rb

Lines 16 to 22 in 254ee82

	def resource_type
	self[:resource_type] ? self[:resource_type] : self.opportunity.resource_type
	end
	def resource_sub_type
	self[:resource_sub_type] ? self[:resource_sub_type] : self.opportunity.resource_sub_type
	end

that expands on how we're grabbing from the "parent" Opportunity