windows installation

Hi @haesleinhuepf,

I have some trouble installing clijpy on a Windows machine by using a simple conda installation. Re-reading your installation instructions for Windows:
```
set PATH=%PATH%;C:\Program Files\Java\jdk1.8.0_161\jre\bin\server
copy "C:\Program Files\Java\jdk1.8.0_161\include\win32\jni_md.h" c:\ProgramData\Anaconda3\Library\include
python -m pip install --upgrade pip setuptools
python -m pip install --upgrade cython
pip install pyjnius
pip install pyimagej

set "JDK_HOME=C:\Program Files\Java\jdk1.8.0_161\"

pip install jnius

# get the environment.yml file from: https://raw.githubusercontent.com/imagej/pyimagej/master/environment.yml
conda env create -f environment.yml

conda activate imagej

pip install pyimagej
pip install scikit-image
pip install scipy
pip install numpy
pip install matplotlib
```

I'm just a bit troubled my one thing: at the very beginning you pip install pyjnius and pyimagej in the base environment, then create an environment called imagej and install again pyimagej in there. Is there a reason for this ? My installation has trouble finding the JDK. Does this "double-installation" fix this ? I'm just a bit worried about installing things into the base environment.

Thanks for your help!
Cheers,
Guillaume