Fix Invalid Token

[bartonp]

• Fixes issue OAuth token refreshing doesn't work #5
• Adds being able to not specify the client_secret if you have a valid token. When the functions that use a client_secret are used they will raise 'UnableToGetToken' exception when the client_secret is none.

[coveralls]

Coverage decreased (-1.3%) to 93.878% when pulling c71510d on bartonp:bug-refresh_token into 6735487 on pawelad:master.

[pawelad]

First of all, thanks a lot for taking the time to submit this! Sorry for taking so long to response, I'll try to find some free time today to review it and possibly merge it.

[pawelad]

Could you please Allowing changes to a pull request branch created from a fork? I like the changes but added a couple other things as well.

[pawelad]

Could you please Allowing changes to a pull request branch created from a fork? I like the changes but added a couple other things as well.

My bad, this was already allowed.

[coveralls]

Coverage increased (+0.1%) to 95.288% when pulling c7c7d86 on bartonp:bug-refresh_token into 6735487 on pawelad:master.

[pawelad]

I added the ability to save client_secret in the JSON token file to so it's possible to refresh multiple times, between shell/computer reboots.

Thanks again for the PR, will do a release in a second.

[pawelad]

LGTM