vmw: Initial VMWare Support

Howto use:

   $ capstan run -p vmw ~/Downloads/osv.vmdk
   Created instance: i1396489429
   OSv v0.06-rc2-31-gdf30ec8

   [/]%

Tested on VMWare Workstaion and Fusion.

Signed-off-by: Asias He <asias@cloudius-systems.com>