Updated Paket files to allow build.cmd to work out of the box

[ncryer]

Paket files are outdated in the master branch and consequently build.cmd fails to run. This PR simply replaces paket.bootstrapper.exe and paket.exe with their latest versions, which allow for build.cmd to get the ball rolling.

IMO worth updating since as a F# newcomer, this is the Nth learning resource that no longer works out of the box - another great example is the SAFE Dojo, which relies on a weather api that no longer exists.