Fix test_multipass_copy

The chunk size was set on the wrong driver (source instead of
target). The size of the transfer has been reduced to 100 bytes
instead of 100KB in order to have a much faster test.
Improve test_rules stability

A different was used each time, but the old files were not
deleted. Now the two reps are created before each test.
Use last version of Logbook instead of Onitu's fork
Improve error handling in LocalStorage. Fix #23

Catch errors when calling stat. Except both IOError and OSError in
all clauses.
Add Python 3.4 to tox and Travis
Add custom exceptions in the Plug
Handle exceptions in the Dealer. Fix #24
Use the new exceptions in Local Storage
Update the docs with the new exceptions
Merge branch '#24_handlers_exceptions' into develop
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