Remove binary dependencies and leverage FAKE boot to load FAKE only once.

This PR addresses the following issues with the build:

* No binary dependencies are required to be stored in source control
* The latest versions of FAKE is used
* FAKE is now the only package copied to another folder location in order to detect and prevent subsequent downloads
* build.fsx no longer needs to reference the path to FAKE as it is now included with the call to Fake.exe through Build.proj