Update node webkit builder
Update node webkit builder

On node v0.12, the webkit binary url was incorrect. Updating
the version of the grunt builder fixes the url

kschat/plaidchat,kschat/plaidchat,twolfson/plaidchat,twolfson/plaidchat,mathieumg/plaidchat,bitemyapp/plaidchat,twolfson/plaidchat,bitemyapp/plaidchat,kschat/plaidchat,naps62/plaidchat,mathieumg/plaidchat,naps62/plaidchat,mathieumg/plaidchat,naps62/plaidchat,bitemyapp/plaidchat