Remove key definition in the package loading.

[sstepashka]

Avoid modification of Emacs behavior on the package loading.

In order to follow the coding convention, disable key definition in the package loading

[casch-at]

Hey @sstepashka! Good point. We should however also update the README.org file which mentions it in several places that org-journal-new-entry can be called with the key C-c C-j.

[sstepashka]

Hey @cslux! I updated the document and added "C-c C-j" in org-journal-mode. It was mentioned in the documentation, but seems like it wasn't defined in there.

[bastibe]

As this is a breaking change, it should probably get a (temporary) mention near the top of the README.

Otherwise, looks good to me!