Add logger

[adamkleingit]

Configurable in Provider, for example:
<ReusableProvider logger={NODE_ENV === 'development'}>

By default it's false

[adamkleingit]

Suggestions:

What should be logged:

• Every change to a unit's value
• Which subscribers were triggered

Use colors/grouping if it makes it more aesthetic (see Redux-Logger for example):
https://github.com/LogRocket/redux-logger

@morsdyce @yarindeoh opinions?

[yarindeoh]

@adamkleingit @morsdyce Agreed, it can be a good start point for debugging options