Add RecurrenceForObject model.
Add for_object argument and implementation to update_schedule
update_schedule for_object tests.
Merge pull request #14 from Wilduck/multi-object-recurrences

Multi object recurrences
Factor out update_schedule common code.
Added update_schedule method to LocalizedRecurrence
LocalizedRecurrence.sub_recurrence method.
sub_recurrence tests and django TestCase switch.
newline for flake8
Readme in ReStructuredText
Updated readme to include state tracking examples.
Installation updates and better docs.
Update setup.py and manifest.in for new READMEs.
Localized_recurrence.check_due method and tests.
Rename tests to follow good naming convention.
Rename tests to follow good naming convention.
Added readme explanation for check_due.
Merge pull request #15 from Wilduck/api-and-docs

Api and docs