testbed/arcyon: make test less flaky

Ordering of tasks seems to be a little flaky when they're created within
a short time of each-other.  Work around this by querying only the first
task created during the exercises.

Test Plan:
$ ./testbed/arcyon/exercise_arcyon.sh
Arcyon task-query: fix ordering

It looks like the '--order' option wasn't really finished, fix a crash
and add a new 'arcyon/acceptance_tests.sh' to exercise various options.

Fix the '--status' help.

Test Plan:
$ ./testbed/arcyon/acceptance_tests.sh
Arcyd: refactor, extract ClassicNaming to module

Continue making way for new naming conventions by moving the
ClassicNaming scheme to it's own module.

Test Plan:
$ ./precommit.sh
$ ./testbed/arcyd/acceptance_tests.sh
Arcyd: support chaining branch naming schemes

In order to allow users to transition from one branch naming scheme to
another, we will need to support operating under both at the same time.

Add support for compositing branch naming schemes by chaining them
together.

Test Plan:
$ ./precommit.sh
$ ./testbed/arcyd/acceptance_tests.sh
arcyd/acceptance_tests.sh: extract branch naming

Make it easier to exercise branch naming schemes by extracting the
branch name creation routine into a new, configurable function.

Test Plan:
$ ./testbed/arcyd/acceptance_tests.sh
Arcyd classicnaming: fix collision with r branches

Fix the abdt_classicnaming scheme to not collide with the imminent
r-branch naming scheme, which it will have to share dev/arcyd with.

Add a trivial doctest to ensure 'dev/arcyd/trackers' is left alone.

Test Plan:
$ ./precommit.sh
Arcyd: implement the r-branch proposal

Implement a new branch naming scheme to enable the creation of branches
named like this:

  r/base/description

Which is shorter and easier to type than the classic scheme and also
allows branches with the same base to sort together.

Add a trivial test driver.

Add a repetition in the acceptance tests with the new naming scheme.

Test Plan:
$ ./precommit.sh
$ ./testbed/arcyd/acceptance_tests.sh
Merge branch 'feature/r_branches2' into feature/r_branches