Motivation:
The attribute bitmap+xdr should provide attributes that applied on
file/directory creation. The current implementation in test client code
is broken as bitmask calculation is wrong.

Modification:
Update client code to use bitmap4#of instead of custom implementation.
add a possibility to specify different attributes for file and
directories.

Result:
valid XDR on the wire.

Fixes: #109
Acked-by: Paul Millar
Target: master