Migrate: Can now move tasks to specific workers if CELERY_WORKER_DIRECT=True

Among other improvements, the following functions have been added:

    * move_direct(filterfun, **opts)
    * move_direct_by_id(task_id, worker_hostname, **opts)
    * move_direct_by_idmap({task_id: worker_hostname, ...}, **opts)
    * move_direct_by_taskmap({task_name: worker_hostname, ...}, **opts)
Test fixes
Regenerates expired certificates
Adds a script for generating certificates
Merge branch 'master' of github.com:celery/celery
Tests passing
Updates Changelog
Bumps version to 3.0.2
one sec join in test
Merge branch '3.0'

Conflicts:
	Changelog
	README.rst
	celery/__init__.py
	docs/includes/introduction.txt
On 2.6 we don't have to import with statement from __future__

Conflicts:

	celery/bin/celeryctl.py
	celery/tests/test_app/__init__.py
	celery/tests/test_app/test_app_amqp.py
	celery/tests/test_app/test_app_defaults.py
	celery/tests/test_app/test_loaders.py
	celery/tests/test_app/test_log.py
	celery/tests/test_app/test_routes.py
	celery/tests/test_backends/__init__.py
	celery/tests/test_backends/test_redis.py
	celery/tests/test_bin/__init__.py
	celery/tests/test_bin/test_celeryd.py
	celery/tests/test_task/__init__.py
	celery/tests/test_task/test_chord.py
	celery/tests/test_task/test_registry.py
	celery/tests/test_task/test_result.py
	celery/tests/test_task/test_task_http.py
	celery/tests/test_worker/test_worker_job.py
	contrib/release/flakeplus.py
removes more with_statement imports
Use except .. as exc
Now depends on Python 2.6
Remove Python 2.5 specific hacks
Merge branch 'master' of github.com:celery/celery
Remove channel from delivery_info
Bumps version to 3.0.3
Merge branch '3.0'

Conflicts:
	Changelog
	README.rst
	celery/__init__.py
	docs/includes/introduction.txt
Adds --2.6 option to flakeplus