Proposal: Add title to Cell

I want my cells to display on a single line (think of a long email, it should no overlap the next column). So I rely a `text-overflow: ellipsis`. It works fine. But now the content is truncated. A quick UX fix for that is to use the html `title` attribute, when you hover for a second-ish, a tooltip shows the full content.

I know I can do that with a custom component (which is the solution I went with) but it also feel like something that could belong in the base components. I'd love to do:

```
columns: [
{
label: 'Email',
value: 'email',
title: true
]
```