add require for InternalOAuthError

When an error occurs getting the user profile, a reference error is reported in the console with details stating _"InternalOAuthError is not defined"_.  Looks like InternalOAuthError just needs to be required in the strategy module.
````
/app/node_modules/passport-bluemix/lib/strategy.js:44
            return done(new InternalOAuthError('Failed to fetch user profile', err)
                            ^
ReferenceError: InternalOAuthError is not defined
````