Missing second argument when using WhitelistPaymaster.sol

Hi Open GSN team, 
I just want you to fix a bug when using whitelistpaymaster.

on line 18 on `migrations\2_deploy_contracts.js`  the address `0x90F8bf6A479f320ead074411a4B0e7944Ea8c9C1` is expected to be whitelisted but a second boolean argument must be sent which is missing.
It is fixed on my side, let me know if I can create a pull request. I will be happy to do it :D. 
  