Install on windows

[zbynekwinkler]

I have a working whell of the cdb module for windows and python 2.7. The prerequisite is working mingw installation. The steps I had to take are:

1. remove O_NDELAY from from open_read
2. include fsync implementation
3. compile and install https://code.google.com/p/mman-win32/ to get implementation for <sys/mman.h>
4. add extra_link_args=['-lmman'] to Extension in setup.py
5. change first param in setup.py Extension from cdbmodule to cdb

I am willing to help with the integration if there is an interest.