VMM/password: Post-2to3 fixes. Replaced ….encode('hex') and ….encode('base64') by b64encode(…) and b2a_hex(…). Added some necessary encode() and decode() calls. Fixed NTLM hash generating with non ASCII characters.

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Upgrading vmm
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Upgrade instructions for different versions of vmm.

.. toctree::
   :maxdepth: 1

   upgrade/0.5-0.6
   upgrade/0.4.x-0.5