Configure the default OAuth2 ClientID

[joshstrohminger]

Describe the PR
Allow callers to configure the default ClientID for OAuth2. This just pre-populates the client_id form field in the Authorize dialog. Here is what it looks like using the following line config:

router.GET("/docs/*any", ginSwagger.WrapHandler(swaggerFiles.Handler, ginSwagger.Oauth2DefaultClientID("swagger")))

Relation issue
None

Additional context
This is done by calling the initOAuth function with the configured value if one is provided.

[codecov]

Codecov Report

Merging #209 (99aeaa0) into master (64d8dea) will not change coverage.
The diff coverage is 100.00%.

❗ Current head 99aeaa0 differs from pull request most recent head 36f23f5. Consider uploading reports for the commit 36f23f5 to get more accurate results

@@            Coverage Diff            @@
##            master      #209   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            1         1           
  Lines           93        98    +5     
=========================================
+ Hits            93        98    +5     

Impacted Files	Coverage Δ
swagger.go	100.00% <100.00%> (ø)

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[ubogdan]

LGTM

[ubogdan]

@joshstrohminger would you mind updating the README.md file regarding this feature?

[joshstrohminger]

Sorry I missed the readme update. Let me know if it's not to your liking.

[ubogdan]

LGTM

[ubogdan]

@joshstrohminger Thanks for your contribution.