t2 update: remote updatePath should not be created with path.join(...)

[rwaldron]

This:

var updatePath = path.join('/tmp/', updates.OPENWRT_BINARY_FILE);

Is fine on *nix platforms, because the remote path will have the same structure, ie. forward slash delimiters. When updating from a windows machine, this will result in a windows normalized path (I will post an example directly from my windows machine as soon as I post this)

[rwaldron]

Rick@Rick-PC MINGW64 ~
$ node
> path.join("/tmp/", "other");
'\\tmp\\other'