Fix kernel installation issue

[dsblank]

Since metakernel install changed, you need to do three things:

1. Change __main__.py to:

from .kernel import GnuplotKernel

if __name__ == "__main__":
    GnuplotKernel.run_as_main()

2. Change kernel.py to include:

import sys

class GnuplotKernel(ProcessMetaKernel):
    kernel_json = {
        'argv': [sys.executable,
                 '-m', 'gnuplot_kernel',
                 '-f', '{connection_file}'],
        'display_name': 'gnuplot',
        'language': 'gnuplot',
        'name': 'gnuplot',
    }

3. Change setup.py. It can now remove the extra install complications; for example, see https://github.com/Calysto/calysto_scheme/blob/master/setup.py for example.

Then you can install the kernel through recommended:

pip install gnuplot_kernel
python -m gnuplot_kernel install

[has2k1]

@dsblank, Thank You for the tip-off.