Do not re-query for proposal objects

The first collection of proposal objects seems to be read-only (i.e. no
destructive ops are performed on it, so there should be no need
to do another query.

This cuts loading the barclamp index page down by almost 50% (1500ms -> 800ms
on a warmed-up server).
Move role revision updates to a separate method
Use proper locking for node allocation

save is refactored to accept a code block that needs to be
protected with the role lock. Make use of that in allocate
and convert usages of previous allocate functions accordingly.
Merge pull request #1055 from bkutil/remove_duplicate_query

Do not re-query for proposal objects
Merge pull request #1056 from dirkmueller/master_use_locking_for_allocate

Use Proper Locking for allocate
Canceling edit leads back to node page
Merge pull request #1058 from bkutil/links_in_node_dashboard

BNC#872793 Use links instead of data-href in node dashboard
Display node list in node show view as well

https://bugzilla.novell.com/show_bug.cgi?id=872347#c5

Once in the node show view, there is no easy way to navigate to other
node w/o going to the dashboard.

Display the (uneditable) node list below the node info.

Refactor the fetching of node groups into a separate method, then re-use
it in the show action. Similarly, split out the node list table into a
partial, then render the partial in both the index and the show views.