Updated to use requests and requests_oauthlib

To allow Python3 support.
Also removes quite a bit of multipart post magic.
For file POSTs, rather than signing params and including them in the multipart
form data, just include them as query parameters. This means they'll
be signed automatically by requests_oauthlib.

Non-file POSTs still need the parameters to be sent as form data.
No need to explicitly specify a filename.

Requests can use the file object to determine the filename.
Python3 support
Code tidyup after 2to3 conversion

Moved config parser into its own module
Trailing whitespace removal
We can only support Python2.6 and above
No need to define NotImplementedError, Python has its own.
PyLint fixes

Moved credentials into new Config class
Version bump to 0.3
Fix verbose commandline option
Update README to use Python3-style print function
Merge branch 'python3' into development