Starting to implement server-side subtree functions.
Merge branch 'staging' of github.com:visgence/portcullis into stream_tree
Merge branch 'staging' of github.com:visgence/portcullis into stream_tree
Add tree structure to side_pane streams.

Needs work still, but is functional.
Ammended to remove OrderedDict import, which was not intended until next commit.
Sort the stream tree.
Add group attribute to expandables so 'owned' is not hard coded.
Merge branch 'staging' of github.com:visgence/portcullis into stream_tree