Remove collections package to support Python 2.6
General stats for the global site.
Fix Leaderboard link in community page.
Updated about page to include Global Stats page
Cache the page view
Most active apps and users in last 24 hours added
Template to show the global stats
Fix hours stats zero fill.
Merge pull request #416 from PyBossa/issue-stats

Issue stats
Add documentation for importing a CSV file. Closes #392
Footer help API link added. Closes #402
Licenses links added to the footer. Refs #418

This commit adds footer links to the licenses of the apps, framework, data and general content.
Fix test_web for tos. Refs #418
Allow customizing TOS. Closes #418
PEP-8 fixes. Refs #371
Migration and Model added. Refs #371

This commit adds the migration, updates the model and also the app presenter and tasks to participate.
Update and Create methods updated. Refs #371
Unit Tests. Refs #371
Unit Tests. Closes #371
Updated docs. Refs #371