Issues with Demo / Autoclass import

Hey @haesleinhuepf -

Thanks for all your work so far on this repo - I appreciate you taking the time to make this port. I've been trying to make the demo work properly - I've setup a conda environment following the per-usual pyimagej setup instructions on their repo page. Unfortunately, I seem to be hitting a wall with jnius' autoclass function. Here is some of my code:

```
import sys
print(sys.version)
import imagej
ij = imagej.init('sc.fiji:fiji:2.0.0-pre-10');
from skimage.io import imread, imsave
from jnius import autoclass
import numpy as np

CLIJx = autoclass("net.haesleinhuepf.clijx.CLIJx")
clijx = CLIJx.getInstance();
```

When I run this, I get an issue with finding the correct class for CLIJx:
`Traceback (most recent call last):
File "clijpy-test.py", line 10, in
CLIJx = autoclass("net.haesleinhuepf.clijx.CLIJx")
File "/home/ubadmin/anaconda3/envs/mac-pyimage-test/lib/python3.7/site-packages/jnius/reflect.py", line 208, in autoclass
c = find_javaclass(clsname)
File "jnius/jnius_export_func.pxi", line 28, in jnius.find_javaclass
jnius.JavaException: Class not found b'net/haesleinhuepf/clijx/CLIJx'
`

I've seen other tutorials on using autoclass, but to be honest I don't know too much of the mechanics. I've seen `autoclass('ij.WindowManager')` and similar things use the `ij` prefix, but not sure how to load the CLIJx class.

Curious to see where I went wrong - Hoping it's something simple I missed!