Improve requirements_*.txt
Remove useless pip install in travis
Don't wait for Router and Dealer in test_changes. Fix #22.

We were waiting for rep1's router and dealer to start. This was
causing a timeout after 5s, so all the transfers had been emited
in less than 5s.
This is due to the fact that the router and the dealer only start
when all the changes have been emited.
Seek instead of appending in LC. Fix #20
Fix except clause for invalid JSON file.
Update drivers.rst

Fixed one more typo
Don't use the same session for the rules tests. Fix #36
Refactor multipass_copy
PEP8
Test should now pass
Wait for transfer started
upload_chunk and get_chunk now take metadata instead of filename

upload_chunk and get_chunk were getting the filename as first
argument. This is not wanted as a driver may request informations
from the metadata in those handlers.
add driver google_drive and test
delete tmp file
optimisation driver