Basic text processing

[michelole]

Ensure that Elastic Search is performing basic text processing, such as:

• Plural/singular
• Removing parenthesis

[michelole]

We're using the default standard analyzer. According to the documentation:

It splits the text on word boundaries, as defined by the Unicode Consortium, and removes most punctuation. Finally, it lowercases all terms.

We could switch to the english analyzer, which performs stemming and stopwords removal. It would then handle plurals accordingly.

We need to reindex to apply these changes.

[michelole]

English stemming worsened results form 0,7693 to 0,6884.

It could still benefit from #97, however.