By storing bundles in a sorted dictionary (dictionary + list of keys),
the bundle does not need to be reparsed during installation if it has
already been initialised, and any additional options passed in the
original command are kept.

This changeset is also an initial attempt to stabilise the name vs
spec naming convention, where a bundle spec is whatever is used to
specify a bundle, be it a name, user/name, full uri, etc., and name is
the name of the bundle that will become a directory under the bundles
directory.

closes #1