Improve autocomplete search

- show a search "submit" button
- search for "us history" should find "U.S. History"
- fulltext search in note bodies -- extract important keywords?
- use metaphone and porter stemmer algorithms (like https://github.com/visionmedia/reds)
- add keyword field
- find multiple words when they're out of order
- add arrow w/ text to draw attention to search box
- keep search text in box after the user searches
- add item to autocomplete menu for doing an "exact search". make up/down keys wrap around without doing index 0 (Search box)