Initial vmsp tree editor

Initial vmsp tree editor

__ notes __

now we can retrieve a tree from the server and use it as the basis of
our dijit.Tree widget. Still work to be done. Can't save anything yet.

Note to self: borrow dojo dnd's "copy" operation (as opposed to move) to
mean replacing a node in the tree, rather than adding to the tree.

Re the permissions I changed, actual users of Evergreen hate having as
much granularity as there was before, and it just confuses people trying
to figure out what perms to give to whom.

Note to self 2: add ADMIN_IMPORT_MATCH_SET to ppl

Usability

1) the tree editor will only let bool_op nodes have children

2) you can't put the unset "dummy" node from the leftside onto the tree

incidentally, gave fm objects a toString method that identifies their
classname hint, as an aid to debugging in general