Fix a reference to undefined variable in NodesController

If a role parameter was specified for the index action, the @groups
would be undefined and sort called on nil in nodes/index.html.haml
Merge pull request #851 from bkutil/undefined_reference_in_node_controller

Fix a reference to undefined variable in NodesController
Fixed node allocate on bulk edit
Merge pull request #852 from tboerger/feature/bulk-allocate

+1