Changed name of typeahead

When adding more than one typeahead on a page, each with a different dataset, only the first dataset gets displayed in each typeahead. This patch changes the typeahead name to the DOM id, which fixes this problem
If selection is null, no more error

When I refresh my page after using typahead, the actual selection disappears, yet typeahead expects the previous selection. This patch mitigates this problem by simply making the value an empty string, rather than throwing an exception
Update main.js
Merge pull request #4 from gevious/patch

If selection is undefined, no more error