Added RQ and RQ-scheduler packages to requirements
Refactor: moved all stat-related cached functions to cache module
Added worker script with context
Option to create PyBossa app to run as non-server
Add scheduled jobs if they're not scheduled only
Disable cache to refresh it
Added some tests
Merge branch 'master' into issue-background-jobs-stats

* master:
  add six lib for Ubuntu Trusty
  clean up of libs. Restrict more
  Restrict version dependencies
  Renamed function
  Simplify
  Explanation about flask-sqlalchemy behaviour
  Use category_id instead of category to prevent autoflushing
  Remove use of get_session and use db.slave_session instead
  Attach a slave_session attribute to db, remove get_session
  Remove unused session maker
  Use scoped_session for slave session
  Use Flask-SQLAlchemy 2.0

Conflicts:
	pybossa/core.py
	pybossa/view/stats.py
	setup.py
Create app objects with run_as_server=False for tests
Add warm_cache function to jobs to be executed
Added log messages
Coverage
Refactor
Revert: background job for warm_up_stats for now
Update docs
Several updates in docs
Correction in docs
Don't store keys in Redis for jobs failed to be scheduled
Refactor tests
Merge branch 'master' into issue-background-jobs-stats

* master:
  localhost can fail on OS X (happened here)
  more explanation when an intended error message appears
  fix group variables
  some more comments
  seperate all, vagrant_dev and vagrant_production
  more generalization
  Streamline Ansible provisioning
  use more options for local Ansible
  Create tables only when not existing
  update vagrant docs
  change description slightly
  use plugin vagrant-ansible-local for provisioning
  chdir to /vagrant on bash login
  remove vagrant_start.sh file
  remove not needed Puppet cookbooks
  install redis-sentinel as a service on boot
  Improve Virtualenv handling
  change default IP for provisioning
  Extend Ansible provisioning to match old Puppet config
  First version of Ansible install for Vagrant