Add followers validation
Don't retry validation set after attempting to start when already in progress
Start specifying followers validations [WIP]
Add param abstraction to README
Rename expect_response params to be less ambiguous

- list_properties_present => body_begins_with (specifies an array of objects expected to be found at the begining of the response body in given order)
- list_properties_absent => body_excludes (specifies an array of objects expected not to be found anywhere in response body)

Both options pertain to list responses