Add sync rules in benchmarks
split benchmarks and use logbook
change the launcher in tests.utils to pimp logbook
fix the tests
remove useless fun
Fix the launcher to take a log uri
improve the exceptions in the benchmarks
Fix the multiples copies
fix the benchmark test
Improve the benchmarks. It's now easier to add a new benchmark
add logbook in benchmarks deps
Add manifests to the doc. Fix #27

A manifest is a JSON file describing a driver and its options.
It is mandatory for each driver.
Add LocalStorage's manifest
Add a launcher for the drivers. Store the manifest in the db.

The drivers don't have to implement '__main__.py' anymore, as it
is now common to all the drivers.

The drivers should now export 'start' and 'plug' in their
'__init__.py' file.

This launcher reads the manifest and give it to the Plug. The Plug
stores it in the database.
Update the doc to reflect the drivers' launcher changes.
Validate the options in the Plug using the manifest
Merge branch '#27_manifest' into develop
* Added the set_chunk_size handler call in the dealer
  to allow drivers to force a specific chunk size (restricted
  by some services)
* Added the documentation for set_chunk_size handler