content view - fix content_view_version_environment to properly access view name
content views - simplify environments for rhsm

This commit contains changes so that:
- when a kt_environment is created, a content_view_environment is
  also created, and it is associated with that kt_environment's
  'default content view'

- when a user (via subscription-manager) lists environments,
  the environments listed are based upon available content_view_environments.
  this is now possible, since traditional (kt) environments
  as well as those from promoting views, will exist there

- when a user (via subscription-manager) registers a client
  to an environment, the environment will be determined based
  on available content_view_environments.

note: with these changes when a kt_environment is created,
both it and the corresponding content_view_environment will
point to the same candlepin environment (i.e. cp_environment).