Rewrite gever setup

  - Introduce two zcml directives to configure deployments and ldap profiles.
  - Simplify deloyment form, remove multi-client configuration options.
  - Add custom setuphandlers for local roles, initial repository and document templates.
  - Configure development options and add environment variable to enable them easily.
  - Update branding, add onegovgever logo.

Closes #368
we need the document-template fix, otherwise the initial version will be broken. i'll rename the ``document_templates`` setuphander to ``opengever_documents`` to indicate that all documents need to be imported like this.