- removed zypper version check from KIWIManagerZypper backend
- Make setup of repotype an optional value:

  * the <repository> section is now allowed to be specified
    without a type attribute
  * the --set|add-repo commandline switches are now
    allowed to be specified without --set|add-repotype

  if zypper is used as package manager and no type is set for
  the repository the zypper auto detection is used. In case of
  any other package manager the default repository type rpm-md
  is used. An information about the selected type is printed if
  no type is explicitly set

  In a sequence of repositories added via commandline arguments
  using --add-repotype still requires to specify the type for
  all given repositories in order to be able to correctly
  assign the type to the added repository in the same way as
  this is required for alias and priority information