Add the ability for the user to 'plug-in' custom modules apart from serving the build-one

Currently in Android and JS land, the user has the ability to plug-in custom modules e.g. custom Pipe/Authenticator/DataStore instead of serving just the "build-ones'

It will be nice if the same is offered in iOS too. Since all impl. share module's each appropriate protocolm enhancing the interface to support pluggable 'add' should be considered.