Use the now() from the underlying schedule in ScheduleEntry

If a schedule defines a custom nowfun, then the ScheduleEntry should use that instead of the app default
Fix broken merge
pep8: Ignore E126,E127,E128
flakes
Fixes flakes E126,E127,E128
changed chdir to cd
Extend Task.rate_limit to accept float values

Celery is enforcing rate_limit integer values, but the kombu TokenBucket implementation
fill_rate value is casted to float anyway, therefore remove this limitation.
Merge branch '3.0'

Conflicts:
	celery/app/abstract.py
	celery/app/amqp.py
	celery/app/base.py
	celery/app/builtins.py
	celery/app/defaults.py
	celery/app/log.py
	celery/app/registry.py
	celery/app/task.py
	celery/app/utils.py
	celery/apps/beat.py
	celery/apps/worker.py
	celery/backends/__init__.py
	celery/backends/amqp.py
	celery/backends/base.py
	celery/backends/database/dfd042c7.py
	celery/backends/mongodb.py
	celery/backends/redis.py
	celery/beat.py
	celery/bin/base.py
	celery/bin/celery.py
	celery/bin/celeryd_detach.py
	celery/bin/multi.py
	celery/bin/worker.py
	celery/canvas.py
	celery/concurrency/base.py
	celery/contrib/migrate.py
	celery/events/__init__.py
	celery/events/cursesmon.py
	celery/events/dumper.py
	celery/events/state.py
	celery/five.py
	celery/loaders/base.py
	celery/local.py
	celery/schedules.py
	celery/security/serialization.py
	celery/task/base.py
	celery/task/http.py
	celery/task/sets.py
	celery/tests/app/test_app.py
	celery/tests/app/test_control.py
	celery/tests/backends/test_cache.py
	celery/tests/backends/test_database.py
	celery/tests/bin/test_amqp.py
	celery/tests/bin/test_beat.py
	celery/tests/bin/test_celery.py
	celery/tests/bin/test_multi.py
	celery/tests/compat.py
	celery/tests/concurrency/test_concurrency.py
	celery/tests/slow/test_buckets.py
	celery/tests/tasks/test_chord.py
	celery/tests/tasks/test_tasks.py
	celery/tests/utilities/test_datastructures.py
	celery/tests/utilities/test_imports.py
	celery/tests/utilities/test_info.py
	celery/tests/utilities/test_pickle.py
	celery/tests/utilities/test_platforms.py
	celery/tests/utilities/test_term.py
	celery/tests/utils.py
	celery/tests/worker/test_control.py
	celery/tests/worker/test_hub.py
	celery/tests/worker/test_worker.py
	celery/utils/__init__.py
	celery/utils/compat.py
	celery/utils/dispatch/saferef.py
	celery/utils/log.py
	celery/utils/mail.py
	celery/utils/timer2.py
	celery/utils/timeutils.py
	celery/worker/__init__.py
	celery/worker/bootsteps.py
	celery/worker/buckets.py
	celery/worker/consumer.py
	celery/worker/control.py
	celery/worker/heartbeat.py
	celery/worker/job.py
	celery/worker/state.py
	pavement.py
Fixes test
Fixes mongodb tests
Updates Changelog
Bumps version to 3.0.13
Now depends on Kombu 2.5.4
Merge branch '3.0'

Conflicts:
	Changelog
	README.rst
	celery/__init__.py
	docs/includes/introduction.txt
	requirements/default.txt
	setup.cfg
Merge branch 'master' of github.com:celery/celery
Fixes security tests
Add myself to Contributors (pull request 1142)
Merge pull request #1143 from cmclaughlin/master

Init script: changed chdir to cd for portability
Merge branch 'master' of github.com:celery/celery
Merge pull request #1138 from rslinckx/patch-1

Use the now() from the underlying schedule in ScheduleEntry