Support for usergroup attributes

[offtherailz]

Description

As an administrator I need the possibility to associate attributes to user groups.

Acceptance criteria

• Attributes can be edited by the usergroup manager, in the group window, in a new tab (general, members, attributes)
• Through GroupManager plugin configuration I should be able to configure:
  • The attrributes to insert
  • The tool to use
• Tools should be :
  • Text input
  • Text Attribute
  • Select (single or multiple)
  • Date
• Each tool should allow to insert single or multiple values of the same attribute key (multiple attributes with the same key are allowed)
  • for input/text area, multiple values can be separated defining a separator: e.g. , or ; for text input `n` for text area
  • For select, the values can be stored in a single attribute, with a separator, or in multiple attributes.
• This configuration must be documented in the GroupManager plugin documentation
• The same configuration of the GroupManager can be applied for UserManager

Other useful information