[MERGE] Change ls-shelf to shelve --list

[Robert Collins]

Robert Collins has voted tweak.
Status is now: Conditionally approved
Comment:
+    def run_for_list(self):
+        tree = WorkingTree.open('.')

I think WorkingTree.open_containing('.') would be better here; and 
perhaps allow a parameter for a tree to list -
bzr shelve --list /foo/bar
would be nice.

The former - use open_containing - I think is needed. Allowing a 
parameter is optional

For details, see: 
http://bundlebuggy.aaronbentley.com/project/bzr/request/%3C49361A08.6090503%40aaronbentley.com%3E
Project: Bazaar