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
Send email to project owners.
Merge branch 'master' into issue-927-clean-old-projects
Add contacted column.
New jobs for handling the old projects.
PEP8 compliant
Refactor.
Tests for get_non_updated_apps.
Tests for sending emails to project owners.
Alternative to test mail.
Refactor
Remove as it is now in test_jobs module.