Cleanups
Docs: Add note on how to disable amaGama service
Docs: Add syntax highlight for examples
Migrations: Only delete unique constraints when appropriate
Migrations: Only delete profile_id column if it exists
Permissions: Use User in PermissionSetForm
Styleguide: Get rid of a deprecated import
Permissions: Update a comment
Migrations: Add migration dependencies for Suggestion migration
Migrations: Fix Suggestion data migration to run on old MySQL instances
Migrations: Improve dependency chain on postgres
migration: fix *_name migrations

This fixes the lack of first_name, last_name in this migration.
Accounts: Add a custom User class
Migrations: Update all migrations to point to accounts.user
Migrations: Also check for the presence of pootle_app_pootleprofile table
Migrations: Do not create a profile_id column in PermissionSet
Accounts: Use full_name instead of first/last name
Accounts: Implement User.display_name
Accounts: Move gravatar_url() to User model
Accounts: Get rid of PootleProfileManager