content views - only show library repos when fetching available
Content Views Rework: updating publish to use the new filter models

This commit contains the changes to allow the publish process
to use the new filter models for packages, package groups and
errata.

This commit does not include puppet modules.  Since those
are no longer handled as a 'filter', a separate commit
and pull request will add them.
Merge pull request #3753 from bbuckingham/cv-rework-filters

Content Views Rework: updating publish to use the new filter models
Merge pull request #3758 from jlsherrill/repo_list

content views - only show library repos when fetching available
Content Views Rework: prepend content_view on filter models, update routes

This commit addresses the following:

1. Rename the filter models/schema, prepending 'content_view_' to each.
   This change is to be consistent with other models
   (e.g. content_view_environments) as well as to ensure that there is
   never a name clash with the core or future models added to katello

2. Update routes to also account for the above change.  For example,
   rather than define:
   GET /filters/:id
   defint:
   GET /content_view_filters/:id