Configures wether to have .env source .rc

def _configure_env_source_rc(config):
    """ Configures wether to have .env source .rc """
    config.set('global', 'env_source_rc', False)
    if system.is_osx():
        logger.info("On OSX, login shells are default, which only source sprinter's 'env' configuration.")
        logger.info("I.E. environment variables would be sourced, but not shell functions "
                    + "or terminal status lines.")
        logger.info("The typical solution to get around this is to source your rc file (.bashrc, .zshrc) "
                    + "from your login shell.")
        env_source_rc = lib.prompt("would you like sprinter to source the rc file too?", default="yes",
                                   boolean=True)
        config.set('global', 'env_source_rc', env_source_rc)