Allow configurable access_lifetime and refresh_token_lifetime for default JWT tokens

[quintonparker]

Allows the default access_lifetime and refresh_token_lifetime values to be overriden when default JWT tokens are implied in the following OAuth2\Server configuration

$server = new OAuth2\Server($storage, array(
    'always_issue_new_refresh_token' => true,
    'access_lifetime' => 316,
    'refresh_token_lifetime' => 499,
    'use_jwt_access_tokens' => true
));

Without this patch the specified access_lifetime and refresh_token_lifetime values is ignored

[bshaffer]

Good catch, thanks!