Use same method signature used in subclasses
Refactor: change if condition for readability
Move try/except one level up and redirect on task load success
Added test to check for redirect after task addition
Remove outdated comment
Fix: forbidden for 403
Import tasks in the background if they're many
Use constant value defined in module
Add job for import tasks in the background
Pass app id to import tasks job
Merge branch 'master' into issue-956-job-importers

* master: (157 commits)
  add note regarding virtualenv
  Simplify Vagrant and Ansible file
  Use repositories for user authentication too
  Small bugfixes and refactor
  Refactor: move repositories to core and extensions
  Use repositories in form validators too
  Remove unused import
  Remove unused things
  Cleaned up imports and refactor base factory class
  Remove moved file
  Split test in 2 to isolate and small fix
  Commit to amend later please
  Use only one scoped_session if there's no slave DB node
  Refactor: extracted classmethod to base class
  Inherit from base class
  Remove base class _create method
  Refactor: moved function inside its only use context
  Removed references to Featured throughout
  Update default theme
  Fix test: don't register the same user twice
  ...

Conflicts:
	pybossa/view/applications.py
Use repositories
Use repositories
Rename constant
Change email content if no new tasks added
Rename constant
Merge branch 'master' into issue-956-job-importers

* master:
  Fix test names
  Delete file commited by mistake
  Use limit and offset in repository method calls in API
  Add limit and offset to all repositories filter_by and order result
  Add limit and offset to task repository filter_by methods
  Test project dependant resources are deleted when deleting project
  Delete associated taskruns when deleting tasks
Refactor: raise exception from within importer
Refactor: remove useless flags
Refactor, extract class to create tasks