Add task to reload users avatars
Upgrades 0.3.0 tag for cartodb postgres extension
Write in log file avatar reload task results
Merge pull request #590 from CartoDB/upgrade_cartodb_extension

Upgrades 0.3.0 tag for cartodb postgres extension
Several fixes in permission mailer
Tests for permissions comparissons
Tests for organization mailing
Fixed mailing urls
Stub notify_permissions_change in vis test

It's actually not necessary to have this method run in order to check
permissions of a visualization
Username in shared visualization url is the owner