Introducing retained flag in modules so they are retained even when the component is unmounted

Introduced a retained flag in IModule that is respected by the RefCounter to keep the module for infinity.

#76: We were not applying ALL of the context values that were provided from ReactReduxContext, so do that here.
When using the createStore prop, we were not providing a modified context to the first connected component. Now, if we call createStore and render a Provider, we will render another instance of DynamicModuleLoader, which will actually add the modules.
While writing this PR, I also decided to simplify the component by removing support for react-redux@5

v3.5.0 with support for React StrictMode

1. We now support React StrictMode. If you render DynamicModuleLoader within a React.StrictMode component, make sure to supply the strictMode={true} prop. Note that DynamicModuleLoader will render twice because it now adds the modules after mount.
2. We also fixed an error where modules where not unloaded in reverse order of add.
3. Other various bug fixes.

Note: This is the first time we are trying to add release notes using Publish Release, fingers crossed everything goes well :).