Normalize Languages for Searching?

[DanielJDufour]

** Note: You may have already done this but I can't test because of #273

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In order to do server-side filtering of the thousands of repos, we need to have a way to search by the normalized (i.e. lowercase) spelling of languages.

Describe the solution you'd like
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I'd like to be able to search https://api.code.gov/repos?api_key=DEMO_KEY&languages=javascript and have it return all of the repos that are JS regardless of whether incorrect capitalization was used (e.g., Javascript, javaScript)

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We probably just need to add a .toLowerCase a couple times on the back-end.

Additional context
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This is really important because the browse projects page in the redesign won't work without it.

[froi]

Normalize languages for Searching?