Store ignored words in sessionStorage


### Problem

The user runs spell check, and ignores a word. They then continue to type and run the spell check again, the same words they've already ignored will be flagged again.

### Proposed Solution

Stores ignore words in the DOM `sessionStorage` object and remove from mis-spells list when the spell check is run. The isn't permanent storage, once the browser is closed completely these will be lost but I think permanently storing them might be an issue.

### Other

Also removed some stray div tags from the examples, and ignored OSX hidden files