Mega.py

------------------

- Fixes broken `download` method.
- Changes `download` and `download_url` methods to return the path to
the downloaded file, previously returned `None`.
- Added LICENSE.

------------------

- Reverts, "Replace pycrypto dependency with pycryptodome" as breaks
login process.

------------------

- When a request fails due to EAGAIN response, retry with exp backoff
up to 20 seconds.
- Adds logging, removes print statements.
- Replace pycrypto dependency with pycryptodome.
- Removes Python 2 specific code.

------------------

- Removes broken method `get_contacts()`.
- Adds support for login with a v2 Mega user account.
- Adds `export()` method to share a file or folder, returning public
share URL with key.
- Adds code, message attrs to RequestError exception, makes message in
raised exceptions include more details.
- Alters `create_folder()` to accept a path including multiple sub
directories, adds support to create them all (similar to 'mkdir -p'
on unix systems).
- Adds `exclude_deleted=True` optional arg to `find()` method, to
exclude deleted nodes from results.

-------------------

- Python 3 bugfix to `upload` method.

-------------------

- Python 3 support and bugfixes.
- Update packaging code.
- Added changelog.