MODE-1667 Changed RepositoryFactory so that it does not have "dual" functionality: that of a container and that of a repository factory. Created a new service interface & implementation named RepositoriesContainer which exposes the kind of operations that are required by the web extensions.
MODE-1667 Updated RepositoryManager to make use of the constants defined in the RepositoriesContainer interface.
MODE-1667 Updated the Javadoc of the RepositoriesContainer interface and added back the "implements Repositories" part to the RepositoryFactory, so that any existing clients aren't broken.