fixes #6373 - make lifecycle_environment_ids accessible

Smart Proxies can now have lifecycle environments, but when adding a Smart
Proxy through the UI, it fails with a mass assignment error.
fixes 6415 - ignore non-bootable distributions in content view

ignoring:
  a) as part of validation to not allow 2 dists with the same arch and version
  b) as part of calculating the kickstart url for a new host
fixes #6477 - fixing host/smart proxy association
Fixes #6490/BZ1116143 - remove unsed Katello javascript.

Remove the old Katello javascript that has since been replaced
by Bastion.

http://projects.theforeman.org/issues/6490
https://bugzilla.redhat.com/show_bug.cgi?id=1116143
Fixes #6391/BZ1091844 - use complete links for content search.

The links for content search were missing part of the required
structure for the "back to results" button to function correctly.

http://projects.theforeman.org/issues/6391
https://bugzilla.redhat.com/show_bug.cgi?id=1091844
Merge pull request #4394 from waldenraines/6391

Fixes #6391/BZ1091844 - use complete links for content search.
Merge pull request #4380 from jlsherrill/6477-proxy

fixes #6477 - fixing host/smart proxy association
Merge pull request #4358 from jlsherrill/6415-dists

fixes 6415 - ignore non-bootable distributions in content view
fixes #6515 / BZ 1107604 - content host package action: disable Perform on empty input

On "Hosts -> Content Hosts -> [somehost] -> Packages", disable the
"Perform" button, unless the user has provided content in the text
input.
Merge pull request #4388 from waldenraines/6490

Fixes #6490/BZ1116143 - remove unsed Katello javascript.
Merge pull request #4339 from stbenjam/6373-proxy-environments

fixes #6373 - make lifecycle_environment_ids accessible
Merge pull request #4398 from bbuckingham/issue-6515

fixes #6515 / BZ 1107604 - content host package action: disable Perform on empty input.