If all you want to do is to play with the sdk to build and test apps (against mock data), then we are currently running a cloud version at https://sdk.iotdatabox.com. We recommend using chrome or firefox. All you need is a github account to get going. Note that if you subsequently want to create your own databox and use the apps that you built in the sdk, you will still be able to get full access to apps that you built in the sdk.
To do a full install of the SDK and databox on your machine, read the following