Impossible to disable server search

Hi, thanks a lot for this tool !
While trying to customize the link-autocomplete tool, I wanted to use it **without** server endpoint.
It appears that, when you do not provide an `endpoint` in the config, the tool still considers that there is actually an endpoint.

I looked at the code carefully and there is a very simple **fix**:
in the file `src/index.js`, the method `isServerEnabled()` lacks the operator `get`.

This is why this kind of expression `this.isServerEnabled ? DICTIONARY.pasteOrSearch : DICTIONARY.pasteALink` always picks `DICTIONARY.pasteOrSearch`.

I hope this can be useful.
Cheers !