INSTALL.Windows: Update build instructions to do 'make'.

We no-longer need to build individual targets on Windows. This information
was lost when we committed the hyper-v changes to the repo.

Resurrecting that information in this change.

Also, added the testing instructions on how to setup a VLAN based network.

Signed-off-by: Nithin Raju <nithin@vmware.com>
Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>