fix(celery): use custom serializer for celery

we use mongo serializer that can take care of ObjectIds and datetimes
Merge remote-tracking branch 'petr/fix-celery-serializer'
fix(io): fix update ingest cmd

it was using superdesk.providers instead of superdesk.io.providers
Merge pull request #255 from ioanpocol/master

SD-248 : Handle data uris on server (fix for webcam)
Add thread per provider in ingest
fix(activity): rename notify to read

it will hold status if a given user has read it

SD-684 SD-656
Merge pull request #257 from petrjasek/master

fix(activity): rename notify to read
fix(tasks) - filter items that have tasks associated.
revert reset pass time to live to 24 hours
Merge pull request #258 from amagdas/fix-tasks-take2-of-n

fix(tasks) - filter items that have tasks associated.
Merge remote-tracking branch 'andrew/master'

Conflicts:
	superdesk/io/commands/update_ingest.py
Merge remote-tracking branch 'adrian/revert-ttk'
fix(celery): make it decode objectid/datetime on load
roles enpoint has been wired - refactored from user_roles
Merge remote-tracking branch 'upstream/master'
fix(celery): make it convert dates/ids within task args

when you will call a task with data from mongodb you will get the same in the worker
Merge pull request #261 from akintolga/master

Renamed user_roles to roles
Merge pull request #262 from petrjasek/master

fix(celery): make it convert dates/ids within task args
(fix) Set the times correctly in the AFP feed
fix(setup): update dependencies