Remove Alfresco repository.

Activiti appeared in Central so Alfresco repository is not needed
anymore.

Change-Id: I1a8139420db7fb6611b9a33c9131ac8af71a5c2d
Fixes: #6
Reviewed-on: https://pirx.atteo.com/gerrit/465
Tested-by: Mr. Jenkins
Reviewed-by: Sławek Piotrowski <sentinel@atteo.com>