Bumped required version of pycomber in order to use build-in support for mergind NoneType with comples types (list, dict, set, etc)
Moved loading default strategies to separate method called only when cli.py is used as executable
Refactored plugin_manager to be more general and do not use hardcoded interfaces; Refactored template_renderer and content_parser accordingly
Factored 'merger' provider out of AppBindingSpec to own 'strategy' module
Moved AppBindingSpec from contentmakeup.binding_spec to contentmakeup.strategy.app_initializer
Instead of directly loading binding_specs special 'rendes vouz' point was created for them (contentmakeup.binding_specs.BindingSpecMountPoint) so now providers can be loaded dynamicly
Removed unused module contentmakeup.template.binding_specs
Ordered plugin alphabetically