Installing Omnipay/payu with laravel 5.1

I am developing a website using Laravel 5.1 and i need to have a shopping cart set up, i am trying to install Omnipay for this, i have selected three gateways i will be using: Paypal, Stripe and PayU. My require under composer.json looks like this:

"require": {
    ...
    "ignited/laravel-omnipay": "2.*",        
    "omnipay/paypal": "*",
    "omnipay/stripe": "*",
    "omnipay/payu": "*"
},

And i am getting error on the payu part alone, this is the error:

The requested package omnipay/payu * is satisfiable by omnipay/payu[dev-master, 2.0.x-dev] but these conflict with your requirements or minimum-stability.

I read on another post that specifying "prefer-stable": true, and "minimum-stability": "dev" into the config part of the composer.json would fix the issue but its not working for me, any tips?

via Chebli Mohamed