Hub: display APIs.guru vendor extensions

[IvanGoncharov]

You can add x-apiClientRegistration it links to a page where you can get API key.
Not all APIs currently have it, but I try to add it for all new APIs.

Also x-unofficialSpec pretty important it's mean that this spec is not from official source.

This is more advanced by you can use x-providerName to group APIs.

[darosh]

@IvanGoncharov thanks for suggestions!

• apiClientRegistration added to hub already (it is in the Versions card)
• apiClientRegistration added to Material Swagger UI
• unofficialSpec added (did not know about that)
• grouping is interesting idea, try the folder button http://darosh.github.io/angular-swagger-ui-material/hub/#?group

[darosh]

@IvanGoncharov added grouped groups only to search examples