Pass sub_parser object to PlatformCleaner add_argument methods.
Require all cleaners to set up a sub parser in order to run

Without this, all cleaners would run each time cleanslate is called.
This behavior is generally undesirable, so, cleaners may now
set a class variable 'sub_parser_name' to register a sub_parser
which is detected at run time. This ensures that only cleaners
which the user has specified by name are run.
Missing __ in magic method name.
Merge pull request #4 from mrrrgn/require-subparser

Require subparser