Go-github: Remove deprecated authentication API endpoints and add replacements

[gmlewis]

GitHub Developer API announcement:
https://developer.github.com/changes/2019-11-05-deprecated-passwords-and-authorizations-api/

This would be a great PR for any new contributor to this repo or a new Go developer.
All contributions are greatly appreciated!

Feel free to volunteer for any issue and the issue can be assigned to you so that others don't attempt to duplicate the work.

Please check out our CONTRIBUTING.md guide to get started.

Thank you!

[waseem18]

@gmlewis I'd like to take this up.

[gmlewis]

OK, thanks @waseem18 - it is yours.

[mubeenflora]

@waseem18 Are you working on it ? i just want to know because i would like to do this

[waseem18]

@mubeenflora Go ahead, I've started work on it but didn't get a chance to complete it.

[mubeenflora]

thanks but it'll take time because i have started my new project

[pavan541cs]

@mubeenflora Are you actively working on this ? Else I would love to work on this

[yashLadha]

Is this issue still up for grabs? @gmlewis

[gmlewis]

With no response from @mubeenflora in two days, I'm opening this issue back up.

[pavan541cs]

@gmlewis I am picking this one and start working on this. Thank you for the update and can you assign it to me

[gmlewis]

Thank you, @pavan541cs! It is yours.

[pavan541cs]

@gmlewis #1360 Can you check this PR and tell me if this looks good so that I can make all the changes. I have done only for one endpoint

[gmlewis]

In another PR, I think it helped (me, at least) to list the things that need to be done to complete an issue. So to complete this issue... (note that this checklist is now being used on #1461)...

The following endpoints need to be removed:

• [x] GET /authorizations
• [x] GET /authorizations/:authorization_id
• [x] POST /authorizations
• [x] PUT /authorizations/clients/:client_id
• [x] PUT /authorizations/clients/:client_id/:fingerprint
• [x] PATCH /authorizations/:authorization_id
• [x] DELETE /authorizations/:authorization_id
• [x] GET /applications/grants
• [x] GET /applications/grants/:grant_id
• [x] DELETE /applications/grants/:grant_id
• [x] GET /applications/:client_id/tokens/:access_token
• [x] POST /applications/:client_id/tokens/:access_token
• [x] DELETE /applications/:client_id/tokens/:access_token
• ~DELETE /applications/:client_id/grants/:access_token~ - it looks like this one was never implemented :smile:

The following endpoints need to be implemented:

• [x] POST /applications/:client_id/token
• [x] PATCH /applications/:client_id/token
• [x] DELETE /applications/:client_id/token
• [x] DELETE /applications/:client_id/grant

Thank you, @pavan541cs for continuing to make progress on #1360.

[clarkbynum]

Any updates on this @pavan541cs @gmlewis ? I'd be happy to help out with the PR

[gmlewis]

Hmmm... it looks like #1360 may have stalled.
Thank you for the ping, @sh3nan1gans.

Let's wait a day or two for @pavan541cs to respond, and then maybe we'll just open this issue up again and someone else can tackle it from scratch (since it seems that there were a lot of issues that needed to be resolved in #1360).

[clarkbynum]

FYI @gmlewis I'm going to take a stab at this. I'll be referring to your comments and the current state of https://github.com/google/go-github/pull/1360 for guidance but please let me know if there's anything else I should be aware of.

[clarkbynum]

@gmlewis - please take a look at this PR - https://github.com/google/go-github/pull/1461
Please let me know if there's anything I missed/should change. Willing to make docs updates as well if necessary

[gmlewis]

OK, to avoid confusion (hopefully), I'm going to close the stalled PR #1360 and start reviewing #1461 so I can use the checkboxes above to help with the review since this is a non-trivial PR. Thank you, @sh3nan1gans, and thank you @pavan541cs for the initial work you did on #1360.