Fix error in LocalStorage on Windows. cf #74
Cleaning some files
Handling plug in dropbox driver
setup.json using dropbox
Changing the chunk upload method
Fixing the upload on dropbox driver
Adding deletion on Dropbox driver
Adding tests
Add init file for the tests in dropbox
Fix the imports in the tests of dropbox
Start of a new approach.
New approach working base : get_chunk, upload_chunk.

- Fix the __init__

- Add a README and a manifest.json

- Add a script to retrieve an access token. Onitu now takes the
  access token key and secret as options to work.
Add the renewed version of change checking.

There still seems to be some issues with folders that don't exist yet
on Onitu side.

- README update
- manifest update
- PEP8 fix
Fix a typo in local storage test
Take the metadata 'path' name instead of filename in change polling thread.

The problem with the file name is that it's lowercased, and thus doesn't
represent the 'true' file name as Onitu stores it. Fortunately, the 'path'
metadata key contains the unchanged filename.

- Store the revision after each upload end. It permits to keep Onitu's
  revision up-to-date and to not trigger a change detection in the change
  polling thread.

- Add more comments

- Do the prefix handling stuff once and for all instead of once per loop
  turn in the check polling thread

- More error handling
Add the abort_upload, delete_file and move_file handlers.

- Add the 'remove_upload_id' helper function

- Changed the get_chunk 'files/dropbox' appending to be done to every
  filename. It wasn't done if the stored filename was already beginning
  by this string, but this could've been error-prone if the user decided
  to reproduce the same file tree & folder names

- Manage the 'has_more' corner case with deltas when checking changes

- Add more error handling with the ServiceError exception
'has_more' handling wasn't correctly indented in polling thread.
Update the tests and the driver code.

An improvement is that since dropbox method upload_chunk already uses
an internal io stream, actually we don't have to use one on Onitu side

Fix some PEP8 issues.
Some updates in the Dropbox tests

- manifest now stands default timer to 1 minute
Detect the deletions on Dropbox (v1).

The metadata system on Dropbox allows us to detect deletions. When
we get deltas of Dropbox, files with None metadata have been deleted.
One could think that's a problem because the case-correct filename is
contained in this metadata. But Dropbox backups it. So if we request
this file metadata (with the case-incorrect filename), we can still
retrieve it. From it, we can recover the 'true' filename and notify
the plug thanks to it.

- Add some functions in the test Dropbox driver