Search v1

[kieraneglin]

What's new?

• Adds a media search method that uses postgres' fulltext search to look at media titles and descriptions
• Adds a description field to media_items and populates it on index/download
• Adds a truncate method to StringUtils for cutting text to length and maybe adding ...
• Adds UI to render a search page including highlighting the relevant excerpts for each search result

What's changed?

• Updated header template so that the search form actually works
• Updated length(list) > 0 to match?([_|_], list) in a few places. It's a little faster, but mainly it's more elixir-y imo
• Updated header styles to show/hide appropriate elements on all viewport sizes

What's fixed?

N/A

Any other comments?

This is a very basic implementation of search, but it works well enough for now. Like so many other things, the objective is to get it out the door and I'll iterate on the aspects of the app that are lacking