fix wrong home directory

On Windows $HOME is defined as combination of
%HOMEDRIVE% and %HOMEPATH%.

Signed-off-by: Jens Frederich <jfrederich@gmail.com>
support custom home directory

Normally I don't work on the default Windows home directory.
I take a separate drive (SSD) to work on. For instance:

e:\ instead of c:\Users\foo

Signed-off-by: Jens Frederich <jfrederich@gmail.com>
Merge pull request #3 from frederich/custom_home

Custom home