Collaborator Email Notification: Add option

[mariorodeghiero]

@amercader

• [x] add a checkbox option to send or not email to the collaborator
• [x] create tests
• [x] create conditional to send or not email to the collaborator in action.py

Acceptance Criteria:

Given I want to add a Collaborator

When I am on the Add Collaborator window

Than I have the option to check the checkbox labeled “Send a notification e-mail?” to Add Collaborator

Tests:

ckanext.collaborators.tests.test_action.TestCollaboratorsSearch.test_create_collaborator_emails_notification_if_not_send_email ... ok
ckanext.collaborators.tests.test_action.TestCollaboratorsSearch.test_create_collaborator_emails_notification_if_send_email ... ok

Result: