update refresh-token-grant errors

Two different conditions shouldnt throw the same error

Author: chrisfranko

lib/grant-types/refresh-token-grant-type.js

@@ -101,7 +101,7 @@ RefreshTokenGrantType.prototype.getRefreshToken = function(request, client) {
       }
 
       if (token.client.id !== client.id) {
-        throw new InvalidGrantError('Invalid grant: refresh token is invalid');
+        throw new InvalidGrantError('Invalid grant: refresh token is invalid because token.client.id !== client.id');
       }
 
       if (token.refreshTokenExpiresAt && !(token.refreshTokenExpiresAt instanceof Date)) {
@@ -130,7 +130,7 @@ RefreshTokenGrantType.prototype.revokeToken = function(token) {
   return promisify(this.model.revokeToken, 1).call(this.model, token)
     .then(function(status) {
       if (!status) {
-        throw new InvalidGrantError('Invalid grant: refresh token is invalid');
+        throw new InvalidGrantError('Invalid grant: refresh token is invalid, no status');
       }
 
       return token;