Add /revoke route as per RFC 7009

[earllapura]

Added /revoke route as per RFC 7009 which was integrated into bshaffer/oauth2-server-php. Request parameters as outlined in the server library should have 'token_type_hint' which is either 'access_token' or 'refresh_token', and 'token' which is the actual token.

[chadicus]

Just a couple PHPCS errors

FILE: ./src/Revoke.php
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FOUND 2 ERRORS AFFECTING 2 LINES
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  1 | ERROR | [x] End of line character is invalid; expected "\n" but
    |       |     found "\r\n"
 11 | ERROR | [x] Whitespace found at end of line
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PHPCBF CAN FIX THE 2 MARKED SNIFF VIOLATIONS AUTOMATICALLY
----------------------------------------------------------------------

[chadicus]

Merged. Thanks!

[earllapura]

Sorry, I didn't know how to correct the errors. Thanks for fixing them!