v2.3.4: Merge pull request #577 from nmantani/fix-windows-breakage (unofficial release)

Binwalk Bugs Squashed and Windows support is added back. All Thanks to @nmantani for PR#577.

Binwalk has been broken on Windows since the commit 0d6bf60 due to import of pwd module that is not available on Windows. I have added checks whether pwd module is available or not with os.name variable. pwd module is available if os.name is "posix" (on Linux, FreeBSD, and so on). On Windows, os.name is "nt". This pull request fixes the issues ReFirmLabs#547 and ReFirmLabs#562.

The following tests used the latest code of the commit fa0c0bd

Release includes:
Windows x64 self contained portable binary.
To build yourself type:

# Binwalk needs to be installed and built first
# python3 setup.py build
# python3 setup.py install
pip install pyinstaller
pyinstaller \
    --onefile build\scripts-3.7\binwalk \
    --name binwalk \
    -p build\lib\binwalk \
    --distpath . \
    --workpath pyinstaller_work_folder