Duplication in JwtBearer Grant

Corrects duplicate check in the validateRequest method found in #172
Merge pull request #173 from Rockstar04/patch-1

Duplication in JwtBearer Grant
make user_id not required for refresh_token grant
Merge pull request #174 from trickleup/develop

make user_id not required for refresh_token grant
Require refresh_token in getRefreshToken response
Require refresh_token in getRefreshToken response

Added "identifier" to description.
Merge pull request #176 from trickleup/develop

Require refresh_token in getRefreshToken response
Update Redis.php

Fixes #180 - case correction for JWTBearerInterface
Update Mongo.php

Fixes #185 - mongo credentials check
Fix wrong redirect following authorization step, refs #171

Fix for #163 (https://github.com/bshaffer/oauth2-server-php/issues/163) allowed
authorize flow to handle `redirect_uri` as an optional parameter. The change
resulted in user not being redirected back to the client after granting or
denying client's access.

This fix verifies whether `redirect_uri` is set or not in
`OAuth2\Controller\AuthorizeController`'s `handleAuthorizeRequest()` method.
If it's not set, it grabs the client's registered value.

If/When support for PHP 5.3 is dropped, the code can be modified to
`$this->clientStorage->getClientDetails($this->client_id)['redirect_uri']`.
Add unit test to check redirect_uri value, refs #171, refs #163