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
@deiferni as discussed, better naming would be helpful here. Both `ident` and `attr` are pretty ambigous. `ident` -> `title`, `attr` -> `config_dict` would be my suggestion.