Add send_mail job
Send mails as background jobs
Migration to add updated and completed columns.

This migration adds two columns: updated and completed.

Updated is used to keep track about when the project was updated (task,
task_runs, etc.).

Completed is used to know when all the tasks have been marked as completed.
Add two columns: updated, completed.
Update timestamp onupdate event.
Add new update_timestamp method.
Update project.updated timestamp when inserted or updated blog post.
Refactor.
Update project.updated timestamp when new task or updated one.
Update app.updated column when taskrun inserted or updated.
Merge branch 'master' into issue-927-clean-old-projects
Fixes in tests
Rename get_all_jobs to get_scheduled_jobs
Send email to project owners.
Update theme
Merge branch 'master' into issue-background-jobs-mail

* master: (22 commits)
  Update theme
  Remove redundant app contexts
  Removed User helper
  replace git ssh address with https. Better for non auth users
  Update docs with rq dashboard
  Fix in docs: use bash syntax
  Use UTC time.
  remove code fixed by new rq-scheduler version used
  Use forked rq-scheduler repository in PyBossa
  Lambdas don't get on well with workers
  Revert: remove warm_cache from jobs for now as it times out
  Temporary fix to create the list of queues in Redis
  Add another job to scheduled tasks
  Add RQ-dashboard blueprint to app
  Add rq-dashboard dependency
  Add tests for access privileges to rq-dashboard
  Update theme
  Use cached version of contributed apps in private profile
  Typo in urls
  Use latin1 decoding for response headers
  ...

Conflicts:
	pybossa/core.py
	test/test_web.py
create user rtester and DB pybossa_test for nosetests in Vagrant
use OS independent DB creation

The manual command in .travis.yml will also work on OS X this way.
Merge pull request #933 from PyBossa/issue-os-independent-db-creation

use OS independent DB creation
Merge pull request #932 from PyBossa/issue-vagrant-nosetester-missing

create user rtester and DB pybossa_test for nosetests in Vagrant