Search

Added a search page with Javascript for searching through posts. The two parameters I used for checking whether or not a post matches the search query are `title` and `tags`. Might want to consider including author info in the `search.json` results. Also this could definitely use some styling cause it's ugly as fuuu.

I tried to keep the Javascript all vanilla and didn't use any external libraries like jQuery. The downside is the code is kinda shitty IMO (not the easiest to read). If we want more features from search (animations or moving the search input to the header and having search results appear in an overlay on any page (ie not having to navigate to `/search` to search for something)) then we should talk about using jQuery.

This fixes #10 
Now that I'm thinking about it `search.json` should really just be `search-data.js` that aggregates the data (like the json file already does) and then assigns it to a variable that `search.js` will assume exists. That way we can put it in `_includes/js` and avoid the network activity of grabbing the file.