added ajaxOptions

[atomfried]

I suggest a small change to src/angularSendFeedback.js which allows to pass an object ("ajaxOptions") which will be merged into the options of the ajax request to the endpoint. This is a generic way to add auth.

Only the first commit should be pulled. However I have no clue how to exclude the subsequent commit from the PR.

M

[atomfried]

PRs are not commit selective, hu. So my suggested commit is 22df003.

I also suggest looking at 4079cc6: it allows to avoid the request for html2canvas.js which is often pointless. Our fix is breaking backwards though.