Config option to disable the stemmer

[nvenegas]

From olivernn/lunr.js#38 there are some cases in which you want to turn off lunrjs's stemmer (e.g., with it on "onboard" is the stem and "onboardi" fails to match it, but "onboarding" matches that stem).

It would be nice to be able to have a config option to remove the lunr stemmer the indexer's pipeline.

[hobzcalvin]

The given method for removing functions from the pipeline is:
index.pipeline.remove(index.stemmer) or
this.pipeline.remove(lunr.stemmer) if within the shortcut initializer
or to create an empty index and never add the unwanted pipeline functions. A config option would be further redundant.

[zephor]

Unless I'm missing something it seems you have to remove the stemmer from the pipeline before the index is built. Currently the index is built by the jekyll plugin in this file: https://github.com/slashdotdash/jekyll-lunr-js-search/blob/master/lib/jekyll_lunr_js_search/indexer.rb

That means we have no control over removing the stemmer before that point. It seems a config option for configuring the indexer is the only option?