transformer: add acculumator transformer

This adds a transformer accumulating counters until a threshold, and then
flushing them out.

This implements a solution to blueprint swift-batched-requests

Change-Id: Ic1f36138d8ee1e5705f2285987763fbff9de0184
Signed-off-by: Julien Danjou <julien@danjou.info>
storage: fix mongo live tests

This closes bug #1124155

Change-Id: Ia8bbcc768d381062df30c93a6d2a7b2089c0efce
Signed-off-by: Julien Danjou <julien@danjou.info>
tests: allow to run API tests on live db

This simplify the database test handling, and allows us to run the API tests
against a real database, revealing brand new bugs!

Change-Id: I39d8c1db5706dcba101799871b89d31e8d51d400
Signed-off-by: Julien Danjou <julien@danjou.info>
mongodb: make count an integer explicitely

This fixes bug #1124350

Change-Id: I389a3f228fd3e1718d242189d9579a3b56852ca1
Signed-off-by: Julien Danjou <julien@danjou.info>
Merge "storage: fix mongo live tests"
Merge "transformer: add acculumator transformer"
Merge "tests: allow to run API tests on live db"
Merge "mongodb: make count an integer explicitely"