support non PY_VERSION config dir names

Hello Perica,

I tried to build a PortablePython distribution with a different set of modules, cause I do not need all the currently included modules and need some additional ones.
So I copied your 2.7 directory with a different (non-numbering) name like 'robot' and made some changes in that configuration files.
 
Starting the  build fails at the end with an error message like 'VIProductVersion must be X.X.X.X'.

Main reason is, that your build scripts used the 'config dir name' hard coded as PY_VERSION
```
 tools\nsis\makensis /V0 /DPY_VERSION=%1 /DPP_VERSION=%PP_VERSION% ...
```
-> the config dir name must be a number 

My suggestion is, that the build script should use the PY_VERSION from the setting.bat file and the config dir name is applied as additional variable PP_TYPE 

```
 tools\nsis\makensis /V0 /DPP_TYPE=%1 /DPY_VERSION=%PY_VERSION% /DPP_VERSION=%PP_VERSION% ...
```

With this change (and some other), it is possible to build distribution file names like ``PortablePython2.7_275.1.0.0`` or
``PortablePythonRobot_275.1.0.283``.

Would it be possible to change your current naming conventions, that non numbering configuration dir names and distribution subnames are supported?

Greetings Luiko