CSV Export IE9 compatibility Fix

[lcampanis]

Hi all,

As the plugin doesn't work in IE9, I took some hints from other similar issues (#3) and created a pull request for you.

Existing tests are failing and so is travis ci for some reason, but the code hopefully works for everyone.

Please let me know how else I can help for this to be merged.

+1 if you'd like it to be merged.

Thanks.

Pull Request: https://github.com/asafdav/ng-csv/pull/150