Transpose references to ReducerList, ReducerObject

[paulmolluzzo]

Problem description:

In the README the names of reducers are transposed from the names being used throughout the code and as file names. In the README they are named PathReducer, ListReducer and so on. Outside of the README they're named ReducerPath, ReducerList, and so on and the file names are like reducer-list. This also becomes clear in the different factory test files for entity types. For example:

https://github.com/raingerber/data-point/blob/7d9e8365dbee9e76ca7949063d1141d1d95d5681/packages/data-point/lib/entity-types/entity-collection/factory.test.js#L8-L11

This was first identified here https://github.com/ViacomInc/data-point/pull/104#discussion_r159443663

Suggested solution:

The naming should be consistent, and it appears that naming them with Reducer at the beginning is preferred. This change will need to be consistent across documentation, comments, code, tests, and file names.

The new names of the reducers with the word Reducer first would be:

ReducerPath
ReducerFunction
ReducerObject
ReducerEntity
ReducerList

[acatl]

since @raingerber's changes they are all reducers now, so this even makes more sense. @raingerber do you see any issues with this?

[raingerber]

No, I think it's a great idea!