Common transformer tests (#97)

* Move chop lump transformer test to a generic log_note_transformer_test

* Add test cases to transformer test

- cat file flip
- cat file pit vow
- deal
- dent

* Move transformer tests over to transformer factor test file

- drip drip
- drip file ilk/repo/vow
- pit file deb ceiling/ilk/stability fee
- price feeds

* Move LogNoteTransformer test into factory package and remove log specific transformer tests

* Move Transformer test into factory package and remove log event specific transformer tests

* Respond to PR comments

pkg/transformers/test_data/mocks/converter.go

@@ -15,6 +15,8 @@ type MockConverter struct {
 	EntitiesToConvert       []interface{}
 	EntitiesToReturn        []interface{}
 	ModelsToReturn          []interface{}
+	ToEntitiesCalledCounter int
+	ToModelsCalledCounter   int
 }
 
 func (converter *MockConverter) ToEntities(contractAbi string, ethLogs []types.Log) ([]interface{}, error) {