handler function for creating inputs & outputs
when Butler.__init__ is called with root,
mapper, mapperArgs

maybe just for now

also change most locations that abbreviated repository
to repo to use full word "repository"

IE make it official. Moves the arg into the repocfg
constructor, and adjusts use cases.

Allows setting mapper in cfg if the cfg is for a
new repo.

they are related to Butler state and don't belong in
an object that gets serialized.

(said 'read only', clearly meant 'write only'; outputs
by default are write only, which is what is done here.)

The new Butler init sequence requires that input repositories
exist. This test was using an input that did not exist, and
it did not matter that the repo did not exist, because the
test is entirely for processing mapper data, that is hard
coded into the test mapper for this test.

Fix is to make the the repo used by the Butler for this test
be an output with mode='rw' instead of an input with mode='r'.

Butler now handles v1 repos in _createRepoData

some of the unit tests use a folder called _parent (instead
of a symlink called _parent to another folder).

The test used to rely on mapper checking before
trying to load repos. The Butler has changed so
that this no longer works, fix the test to
actually create repos.

must have an input repo available to use it as a read-only repo.