Allow OAuth2 session request() to take client_id and client_secret

[singingwolfboy]

Because when doing automatic token refresh, we need a client_id and client_secret in order to do HTTP Basic auth. This is necessary for automatic token refresh with Bitbucket.

[coveralls]

Coverage decreased (-1.7%) to 84.932% when pulling d4e0214 on singingwolfboy:oauth2-request-accept-client-id-and-secret into a116d06 on requests:master.

[coveralls]

Coverage decreased (-1.7%) to 84.932% when pulling a9f142c on singingwolfboy:oauth2-request-accept-client-id-and-secret into a116d06 on requests:master.

[coveralls]

Coverage decreased (-1.7%) to 84.932% when pulling ce3a67b on singingwolfboy:oauth2-request-accept-client-id-and-secret into a116d06 on requests:master.

[coveralls]

Coverage decreased (-1.7%) to 84.932% when pulling ce3a67b on singingwolfboy:oauth2-request-accept-client-id-and-secret into a116d06 on requests:master.

[coveralls]

Coverage increased (+0.1%) to 86.758% when pulling 3348380 on singingwolfboy:oauth2-request-accept-client-id-and-secret into a116d06 on requests:master.

[Lukasa]

Thanks @singingwolfboy, this looks good to me! ✨ Sorry about the delay!

[singingwolfboy]

@Lukasa Thanks! Would you mind releasing a new version of requests-oauthlib? I have a pull request to Flask-Dance that depends on this code, and I can't merge that PR until I can modify the requirements.txt file to point to a version of requests-oauthlib that has this change.

[Lukasa]

Sure, I'll aim to release sometime this week.