allow features to have numeric ids

[mcwhittemore]

Closes #738
Closes #777

@mmoutenot do you take a look at this and confirm I've fixed the bug?

[mrshll]

Sorry for the delay. I reviewed the MR and it looks good 👍

I have not had an opportunity yet to install this branch on my codebase, however.

[jackwkinsey]

I've confirmed that this fix should also address my issue as well!

Thanks!

[mcwhittemore]

@jackwkinsey & @mmoutenot - I've shipped 1.0.9 to npm.

@mollymerp - do version of gl-draw appear in the Mapbox CDN automagicly, or is there a next step I need to take to do that?

[mollymerp]

@mcwhittemore yes they get uploaded automatically by travis, but the version doesn't get bumped on the gl-js examples page. I've tagged you in a PR updating the example page!

[friendlyswiss]

@mcwhittemore thanks for this fix!

It looks like a few methods still only take feature IDs as strings:

-get
-changeMode
-setFeatureProperty

Specifically, I'm running into problems using draw.changeMode('direct_select', 'some_numeric_id').

I'm a non-dev working on a side project, so I'm grateful for any help. Thanks!