Add no-await-in-loop rule.

[nmote]

Closes #20

[nmote]

Friendly ping @jquense @hzoo :)

[hzoo]

Can we actually use Set here since we don't know what version of node people are using?

[nmote]

Do we have a target minimum version? I can use an Object instead of necessary.

[jquense]

there is nothing set in stone but I think we are mostly in keeping with eslint, which still supports 0.10.x i believe...my rule of thumb has been: es5

[nmote]

OK, I removed Sets. I'm not thrilled about iterating over an array to check membership, but I think since the depth of the AST is generally fairly small it shouldn't be a big problem. I used Objects where I could but as I said in the comments, that's not appropriate when the elements aren't strings. I'm happy to entertain other suggestions.

[jquense]

LGTM, I think the array will be fine, bc as you say the depth is not likely to be deep enough to make much of a difference.

If it does pose an issue I'd be happy to revisit using Set, I don't think it would be too much trouble to require node 0.12+ but lets see how it goes.

[jquense]

I'll try and get a release out in the next day or so

[nmote]

@jquense Any word on a release?

[jquense]

sorry about that, been a busy month thanks for the reminder

[nmote]

No worries, I know how it goes 😄