content-deletion - add a promotion/deletion banner to the changeset tree

This is an initial commit to add a banner to the changeset sliding
tree to allow a user to view either promotion or deletion changesets...
Merge remote-tracking branch 'upstream/content-deletion' into fork-content-deletion-3
content-deletion - initial chgs to support 2 changeset trees (deletion/promotion)

This is an initial commit to provide changes to support the appearance
of 2 separate sliding trees for promotion and deletion changesets.

There is more work to be done to get this to work when applying the
changesets...etc.
changesets - fix the locked icon image on changeset list
content-deletion - fix some references to accessing current chgset breadcrumb
content-deletion - load changeset sliding tree based on changeset hash

If the user accesses the changesets page with a changeset hash
(e.g. "#changeset=changeset_10") and that changeset is a
deletion changeset, load the page with the deletion changeset
sliding tree selected; otherwise, use the default behavior which
is to load the page with the promotion changeset sliding tree
selected.
content-deletion - remove the changeset type from the sliding tree listing

Previously we had a single list consisting of all changesets.  In
that listing, we included some text to indicate the type for each
changeset (i.e. deletion/promotion).  Since we are now creating 2
separate lists, that type is no longer necessary; therefore, removing it.
content-deletion - update the content tree to use 'Added (Undo)' vs 'Remove'

This commit contains changes so that when an item (e.g. product, pkg,
errata...) is added to the changeset, the content tree includes
"Added (Undo)" (where undo is a link) vs "Remove".  Although this
affects the content tree (left side), it does not affect the changeset
tree (right side), which will continue to use 'Remove'.

This commit also contains a small fix to allow repos to be removed
from a changeset after they have been added.  Previously there was
a bug where the repo once added was not correctly detected by
the changeset 'has_item' method.
content-deletion - update the content tree to use 'Added (Undo)' vs 'Remove'

This is a follow-up to the previous commit to address the changes needed
to the system templates view.
content-deletion - add title attribute to the changeset action bar

This commit adds the title attribute to the items in the
changeset action bar (e.g. Remove, Edit Details, Review, Promote/Edit).
For simplicity/efficiency, chose to use html title attribute for
these vs creating a tipsy element.
content-deletion - add custom confirms for changeset deletion

Update to have a custom confirm on changeset deletion, so user
is aware of the type of changeset they are deleting.
content-deletion - add a tipsy to the 'Added' item in content tree

Added a tipsy to the 'Added' text in the content tree so that
when user hovers, they see info like "Added to changeset XYZ".
content-deletion - update helptip to include both deletion and promotion
content-deletion - convert action titles to tipsy for consistency

Added title attribute to changeset actions (e.g. Remove, Edit..etc);
however, noticed that tipsy is used in this page quite a bit but
title is not.  As a result, updated them to use tipsy for consistency.
Also, added a 'tipsify' class so that we can have a single instantiation
of tipsy for the tipsies added for the actions, the ones used for
the "Added (Undo)" and others in the future.
Merge remote-tracking branch 'upstream/content-deletion' into fork-content-deletion-3
Merge pull request #468 from bbuckingham/fork-content-deletion-3

content-deletion - changes to UI based on mockups