UsageError: Cell magic `%%kernel` not found.

After installing beakerx through conda I can see the following:

```
jovyan@33e40db3e7ef:~$ jupyter kernelspec list
Available kernels:
julia-0.6 /home/jovyan/.local/share/jupyter/kernels/julia-0.6
clojure /opt/conda/share/jupyter/kernels/clojure
groovy /opt/conda/share/jupyter/kernels/groovy
java /opt/conda/share/jupyter/kernels/java
kotlin /opt/conda/share/jupyter/kernels/kotlin
python3 /opt/conda/share/jupyter/kernels/python3
scala /opt/conda/share/jupyter/kernels/scala
sql /opt/conda/share/jupyter/kernels/sql
```

I can use each of these kernels except Julia with the %%scala, %javascript, etc commands.

As you can see in the screenshot, %%kernel is not found as a cell magic.

I unfortunately do need Julia 0.6.4 since the libraries I require depend on it.

I am running in a Docker container ([Dockerfile here](https://github.com/HIVDiversity/jupyter-rad/blob/master/Dockerfile)) which is based off the official [Jupyter minimal notebook](https://hub.docker.com/r/jupyter/minimal-notebook/) (tag, `83ed2c63671f`, which was the latest yesterday) . It comes with conda included, see version below. I installed Julia 0.6.4 [like this](https://github.com/docker-library/julia/blob/467c652ab40064be58ba83ed4448f139592c7525/0/stretch/Dockerfile).

Some other version info:
```
jovyan@33e40db3e7ef:~$ jupyter --version
4.4.0
```
```
jovyan@33e40db3e7ef:~$ beakerx --version
1.3.0
```
```
jovyan@33e40db3e7ef:~$ conda --version
conda 4.5.12
```
```
jovyan@33e40db3e7ef:~$ uname -a
Linux 33e40db3e7ef 4.15.0-45-generic #48-Ubuntu SMP Tue Jan 29 16:28:13 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
```
And by doing a `conda list` I can reveal the following ipython/jupyter related versions:
```
ipykernel 5.1.0 py37h24bf2e0_1001 conda-forge
ipython 7.2.0 py37h24bf2e0_1000 conda-forge
ipython_genutils 0.2.0 py_1 conda-forge
ipywidgets 7.4.2 py_0 conda-forge
jupyter_client 5.2.4 py_0 conda-forge
jupyter_core 4.4.0 py_0 conda-forge
jupyterhub 0.9.4 py37_1000 conda-forge
jupyterlab 0.35.4 py37_0 conda-forge
jupyterlab_server 0.2.0 py_0 conda-forge
```

This attachment shows my Julia kernel working fine, and it shows it not working in a polyglot environment.


Anything I am not doing correctly? Maybe I am missing steps to install support for Julia. Please let me know if there is any more info I can give.