release 0.34 branch on NPM

[ivanov]

Similar to what happened in #3, the currently available version of @jupyterlab/xkcd-extension yields the following error:

$ jupyter labextension install @jupyterlab/xkcd_extension
> /usr/bin/npm pack @jupyterlab/xkcd_extension
npm ERR! code E404
npm ERR! 404 Not Found: @jupyterlab/xkcd_extension@latest

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/pi/.npm/_logs/2018-08-23T06_07_26_346Z-debug.log

Errored, use --debug for full output:
ValueError: "@jupyterlab/xkcd_extension" is not a valid npm package
~/potatoes $ jupyter labextension install @jupyterlab/xkcd-extension
> /usr/bin/npm pack @jupyterlab/xkcd-extension
jupyterlab-xkcd-extension-0.4.0.tgz

Errored, use --debug for full output:
ValueError: This extension does not yet support the current version of JupyterLab.

Conflicting Dependencies:
JupyterLab              Extension        Package
>=0.18.3 <0.19.0        >=0.17.0 <0.18.0 @jupyterlab/application
>=0.18.3 <0.19.0        >=0.17.0 <0.18.0 @jupyterlab/apputils
~/potatoes $ jupyterlab --version
/bin/sh: jupyterlab: not found
~/potatoes $ jupyter lab --version
0.34.1

building the 0.34 branch of this repo via jupyter labextension install . from source works fine, though.

[masip85]

+1

[bobmayuze]

This issue could be resolved by manually changing the version of the package required in package.json, but I don't think that is an ultimate fix.

[julianrendell]

Still broken on a clean install into a docker image.