moved docs to py/xxx/README.md

Summary: Moved py/abd.md to py/abd/README.md for all packages and updated gen_docs appropriately.

Test Plan: $ rm py/*/*.md && ./gen_doc.sh && cat py/*/*.md

Reviewers: jevripio

Reviewed By: jevripio

CC: phab

Differential Revision: https://sibld.phab.dev.bloomberg.com/D155
Add test plan to abdi_processrepo__t
Arcyd: rm 'clone' from abdi_processrepo interface

To decrease the burden of testing abdi_processrepo, hoist the clone out
and supply the branches to it directly.

This means there is one less thing to mock and less temptation to use
the clone to perform operations in the future.

Test Plan:
$ ./precommit.sh
testbed/arcyd $ ./multi_repo.sh
Arcyd: new-style breathing test for processrepo__t

Start creating tests in abdi_processrepo__t which don't rely on a real
Git repository.

This will start the separation of Git integration concerns from review
branch processing.

Test Plan:
verified that 'Test' and 'OldTest' both execute with nosetests -v
$ ./precommit.sh
Arcyd: introduce mock branch for new tests

To make it easy for us to simulate various situations when testing
abdi_processrepo; supply a mock implementation of abdt_branch.

Test Plan: $ ./precommit.sh
Arcyd: extract conduitmock internals to new class

Make it possible for abdt_conduitmock.ConduitMock to have the same
interface as abdt_conduit but also allow us to meddle with its workings.

Split the internals of the mock out into a separate class, which
ConduitMock will delegate all of its reposonsibilities to; leaving it as
merely a wrapper for the internals.

We may then supply the internals class to the wrapper and do as we wish
with the internals, so long as we retain a reference to it.

Test Plan: $ ./precommit.sh
Arcyd: finish processrepo test_B_Uncomplicated

Fix bugs in the mock implementations to support the new test.
Add some more supporting machinery.

Test Plan: $ ./precommit.sh