spike(services) - introduce services and injected data layer.
spike(services) - update preferences to use BaseService class
spike(services) - create only one instance of EveBackend
spike(services) - rename BaseModel to Resource, move all methods from
Resource to datalayer.py. Renamed endpoint_name to datasource in
BaseService.
Rebase from master, fix item lock and autosave.
fix(remove expired) - use _updated insted of _created
Merge pull request #275 from amagdas/remove-expired

fix(remove expired) - use _updated insted of _created
Merge pull request #268 from amagdas/spike-services

spike(services) - introduce services and injected data layer.
SD-723 user preferences that can be changed
feat(preferences) - create and endpoint to show resource preferences
refactor(users): make users work with citizendesk

make it importable outside of superdesk

SDS-1
Merge pull request #277 from petrjasek/master

refactor(users): make users work with citizendesk
Merge pull request #276 from amagdas/preferences

feat(preferences) - create a way to register per resource preferences and fetch them