system groups - update to have Content as 3rd level nav

This makes Content as a 3rd level nav consisting of Packages and Errata,
consistent with the Systems page.
system groups - update errata and packages partials to use new spinner definition
system - minor refactors for code that will be shared for system groups

This commit contains minor refactorings for some code that will be
shared for system groups.
system groups - initial commit to introduce group events

This initial commit contains some of the pieces needed to support
system group event history (e.g. nav/controller/model/view...etc).

There will be additional commits to complete this logic.  This
includes covering things like status polling from event history
pane, listing of systems on a given event (along w/ status)...etc.
removal of system_tasks, replace with polymorphic assoc on task_statuses

This commit removes the current system_tasks model and associations
between a system and task status.  It replaces it with a polymorphic
association on the task_status.  That association adds a 'task_owner'
to the task status, which any other model can be associated with (e.g. System).
This allows us to associate a task essentially with any other model
without requiring an additional join table (like the current
system_task).

Updated all existing code using system_task to use this new relationship.

Also, created a migration which will add the elements needed for
the relationship (task_owner_type, task_owner_id) to the model,
populate it with appropriate data based upon existing system_tasks
records and then drop the system_tasks.
Merge branch 'master' of github.com:Katello/katello into fork-group_events
system packages - fix event binding

The the unbind that was being done for the +Add and -Remove link
was not correctly unbinding the event.  As a result, it was
possible that multiple events would be generated when the user
clicked those links.  This commit addresses that issue.
system and group actions - replacing .spinner with use of image_tag

Currently using the .spinner on these views does not generated a desired
affect.  Essentially, a div is added causing spinner and status text
to be on separate lines.  For now, to avoid this, going to use the
image_tag direct.  If the issue w/ .spinner class is resolved, this
commit can be reverted.
task status - clean up some of the status messages
system groups - when saving tasks for a job, associate system w/ the task
system groups - events - add a tipsy to show status of a task

This is an initial commit to show the status of completed/failed
task associated with a system group action, via a tipsy.  This will be updated
when status polling is added to add the tipsy when the task reaches completion.
system groups - event/job status updates

This commit contains changes to support polling for status
of jobs scheduled on a system group.  This allows user to
see status of in progress jobs from the SystemGroups -> Group -> Events
pane.
system groups - support status updates on individual system tasks

This commit contains changes so that if the user has
navigated to SystemGroups->[groupX]->Events->[jobY],
the user's client will poll for updated status for any
pending tasks for that current job.

In order to support this, updated the system_events poller
to support polling for both jobs and tasks at the same time.
This minimizes the polling requests.

Note: for the Systems page, this means we'd use tasks, but
for System Groups page, we use jobs+tasks.
system groups - remove tasks class from view
systems - events - update search to include task owner

As part of getting rid of system_task.rb, the system_ids field
was removed from the index.  In order to support searching
for tasks based on system, we can now use the task owner id field.
system events - fix specs related to changes in status retrieval
system group - add some initial search support to group history

This commit contains changes to provide basic search support
for system group event history.  This includes searching based
on username and parameters.  In a future commit, support for search
by status will be added; however, that requires a bit more work,
based on the fact that status is determined by looking across all
tasks related to the job and the way system events currently handle it.
system groups - add few specs for events controller
system groups - remove 'details' on job since it is a dup of as_json
Merge remote-tracking branch 'upstream/master' into fork-group_events