Turn Benchmarker.type into a list of test types

Also create a variable of the keys required for each test type
Update FrameworkTest.runTests
Ensure a minimum set of keys is present in the benchmark_config
DO NOT MERGE (Comment out until #557 is resolved)
Add initial FrameworkTestType classes
Map test type strings to FrameworkTestType objects
Remove deprecated contains_type method
Fix requires_db
Move JSON validation into specific type
Fix bug in header
Replace test description with URL
Create method to verify single type
Moved accept header choice to FrameworkTestType
Move URL selection to FrameworkTestType
Cleanup prerequisites
Create function to benchmark one test type
Move JsonTestType into separate file
Minor improvements to LOC counting
Fix typo in imports
Create PlaintextTestType